Police have linked a suspicious package discovered at the University of Glasgow this morning to the parcel bombs sent to London transport hubs yesterday.
Detectives have made the connection after part of the Scottish campus was shut down and evacuated today while a controlled explosion took place.
Buildings at the University of Essex were also cleared today after a suspicious package arrived, although it was later found to be harmless.
Police Scotland now believe the Glasgow package was linked to the improvised explosives, seemingly sent from Ireland in A4 jiffy bags, which caused a terror scare at Heathrow Airport, London City Airport and Waterloo station on Tuesday.
Students have been evacuated from the University of Glasgow after a 'suspicious package' was discovered in the mailroom
Hundreds of people outside a university building at Essex amid the security alert today
Buildings at the University of Essex were cleared this morning at 11.50am and hundreds of students gathered outside
A member of the bomb squad in body armour is pictured outside the University of Glasgow this afternoon
Police Scotland officer Steve Johnson said: 'There are similarities in the package, its markings and the type of device that was recovered in Glasgow to those in London.
'Therefore, we are now treating it as being linked to the three packages being investigated by the Met in London and both investigations are being run in tandem.'
He added: 'Our enquiries into the Glasgow package are at an early stage but there is no ongoing risk to the public.
'The package in Glasgow was identified by alert staff at the university mailroom who had received protective security information advising them to be vigilant and to report suspicious packages.'
The Metropolitan Police said the latest package contained a 'similar-type device' to those at London's major transport terminals on Tuesday.
The scare in Glasgow began this morning when students were ordered to move away from a campus building after a suspicious package was found in the post room.
One student said: 'Just been evacuated from the med school due to a suspicious package getting told to move to byres road, loads of police, fire engines and all cordoned off now!'
She added: 'Scary stuff, guy just came shouting we needed to evacuate as suspicious package found then the police were shouting at us to move away from the building!!'
Roads around the university were cordoned off by police and buildings including an Officer Training Corps centre were shut down.
The device was blown up in a controlled explosion on Wednesday afternoon after bomb disposal experts were sent to the campus.
The package was not opened and no-one was injured, Police Scotland said.
'Police Scotland officers investigating a suspicious package sent to the University of Glasgow today (6 March) have now linked the incident with a similar investigation being carried out by the Metropolitan Police Service into three small improvised explosive devices sent to addresses in London on Tuesday,' they said tonight.
Essex Police said in a statement that they were called at 11.50am. The force said: As a precaution we have put a 100m cordon in place and have evacuated a section of the university and some nearby buildings'
Police officers have cordoned off roads outside the University of Glasgow
Police have cordoned off roads in the area and fire fighters were also called to the scene
The bomb squad was also called to Colchester after Essex Police received a call about a suspect package at the university.
Police put a cordon in place and cleared out part of the university amid fears of another explosive device.
University chiefs sent for the Ministry of Defence's bomb disposal squad, but later said the package 'posed no risk to the public'.
In Edinburgh, workers at the RBS building in Gogarburn were also evacuated after another suspicious item was found but it proved to be a false alarm.
A spokesman for Police Scotland's Edinburgh division said: 'Police were called to the Royal Bank of Scotland premises on Glasgow Road following a report of a suspicious package inside the building.
'The incident was reported to police at 10.45am on Wednesday and an area of the building has been evacuated as a precaution.'
There was also a brief alert at Westminster as police warned peers and members of the public to avoid the House of Lords because of an unknown item.
The scare at Parliament was over within five minutes as police said they were 'happy to update the item found was non-suspicious'.
Photographs taken at the scene show roads and areas cordoned off outside the university in Glasgow
The university's Boyd Orr Building, the mailroom, the OTC (Officer Training Corps), Wolfson Medical Building, Bower Building, Isabella Elder Building, James McCune Smith Learning Hub site and the Joseph Black Building have all been closed
Another image posted on social media shows a police cordon at the university in Colchester, Essex
Workers at the RBS building (pictured) in Gogarburn in Edinburgh were evacuated at around the same time as students were ushered out of the university. It was later ruled to be a false alarm
Police say explosive devices capable to starting a small fire were sent to Heathrow, London City Airport and Waterloo railway station police have confirmed
An image released today by the Metropolitan Police show the package sent to City Airport yesterday
Pictures shared online show the crude devices packed in envelopes reading simply 'Heathrow' and 'London Waterloo'
Counter terror police are probing possible links to the New IRA over the firebomb plot which saw three improvised explosive devices sent to Heathrow Airport, City Airport and Waterloo.
Searches are ongoing to locate any other similar packages that may have been sent but not yet identified as Scotland Yard circulated two images of the devices to sorting offices and transport workers.
The Met Police, who are investigating the three 'linked' firebombs sent from addresses in Dublin alongside police in Ireland, told staff to 'be vigilant and report suspicious packages to the police.'
The latest parcel bombs risk provoking anti-Irish sentiment in the UK at a highly sensitive time during the negotiations on the border.
It comes as extra 300 officers will be drafted in to Northern Ireland over the coming months to deal with the threat of violence around Brexit.
Intelligence sources in Ireland have been claiming for months that terrorist action may be ramped up to exploit opportunities from Brexit, particularly if it resulted in a hard border which could come into effect after a no-deal withdrawal.
The police cordon at Waterloo Station where the suspicious package was found yesterday afternoon
Security alert: Two police vehicles and several officers at the scene at London Waterloo station on Tuesday after one of the explosives was found at the country's busiest rail terminal
The New IRA, who were behind the Londonderry car bomb in January, also admitted responsibility for a spate of letter bombs sent to British Army recruitment centres in 2014.
Ireland's Gardai police force is assisting the Metropolitan Police with their investigation into Tuesday's parcel bomb plot.
Security sources said there were 'multiple possibilities' for the motive behind the attack, including 'mental health, general protest, grudges' but they have not ruled out dissident republican terrorists.
It comes just months after Police Service of Northern Ireland Chief Constable George Hamilton welcomed the announcement the force was receiving £16million in additional funding which would allow for an extra 308 officer and staff by April 2020.
He had warned that the return of infrastructure to the Irish border could make border posts a target for dissident republican violence.
PSNI chief George Hamilton has warned that the return of infrastructure to the Irish border could make border posts a target for dissident republican violence
The New IRA were responsible for the Londonderry car bomb on January 20, 2019. Pictured: The wreckage of the car that was laden with explosives
The New IRA also admitted responsibility for a spate of letter bombs sent to British Army recruitment centres in 2014. Pictured: The bomb squad outside an army recruitment centre in Brighton
Secretary of State for Northern Ireland said the funding, announced in December, would help manage 'pressures and contingencies arising from EU exit preparations, reflecting the specific and unique concerns in Northern Ireland'.
Speaking in November last year, Mr Hamilton rejected claims that the threat of violence at the border after Brexit was being exaggerated.
He told BBC News that those who say the PSNI or others, are 'overplaying the border and Brexit in policing terms' are 'simply wrong'.
The threat from dissident republican groups is currently graded as 'severe' by the PSNI.
Pictures of the three explosive packages appeared to show a postage stamp issued in the Republic of Ireland.
The word 'Dublin' also seems to be scrawled on the 'return address' section of the envelopes sent to Waterloo, Heathrow and London City.
The heart-shaped 'Love and Marriage' stamp was issued in 2018 and offered as a 'romantic touch' to greetings cards.
A postcard marked with one of the 'Love and Marriage' stamps issued in the Republic of Ireland in 2018
On the letters addressed to Heathrow and Waterloo the stamps are seen to bear the words 'Love' and 'Eire'.
They match the 2018 edition of the annual 'love stamp' issued by the Irish postal service.
The stamps are still for sale on the website of the Irish post office, with ten stamps on offer for €10.00 (£8.50).
Irish police have said they are assisting Scotland Yard with the investigation into the three suspect packages.
The Met's counter-terror command said they are keeping an 'open mind' about a possible motive.
Mr Hamilton said that if the Brexit negotiations resulted in no deal, it would 'magnify all the demands and difficulties' and said that dissident republicans who are opposed to the peace process would try to 'exploit' any hardening of the border - both 'politically and ideologically' and through engaging in organised crime, such as smuggling.
At Westminster today DUP leader Nigel Dodds asked Northern Ireland Secretary Karen Bradley if there was any prospect of the security threat level being raised.
She told the Commons that the threat level was at 'severe' and there was no suggestion it was going to change.
She said: 'I had a conversation with the chief constable this morning and in terms of the specific incident it is the early days of an ongoing investigation, it wouldn't be appropriate for me to say anything further at this stage.'
Mr Dodds replied: 'She will understand the concern that is out there about these devices having been sent through the post.
Officers in Ireland and the UK now hope that forensic examination of the packages will provide clues to the identity of those responsible.
The stamps appeared similar to some issued by An Post for Valentine's Day 2018, featuring a heart motif and the words 'Love' and 'Eire'.
The three 'linked' packages which were discovered within hours of each other, as one of them burst into flames at Heathrow when an airport worker tried to open it, and the others had to be defused by bomb squad officers.
No-one was injured by the packages and there was little disruption to rail or air passengers even as Scotland Yard's Terrorism Command sealed off parts of the transport hubs. No arrests have yet been made.
Security sources said the 'unsophisticated' parcel bombs seemed to have been intended to 'alarm not maim', as police said they were keeping an 'open mind' about the motive.
Sources told the Irish Times that the devices had been sent by post from Dublin, matching what appeared to be a return address written on the envelopes.
One of them purported to come from Bus Eireann, an Irish coach operator, while the other was hard to read. It was not clear whether the return addresses were genuine.
The bus operator said police had not been in touch, adding: 'Bus Eireann are currently not aware of this and we have no further comment.'
The last dissident plot against the British mainland was in 2014 when explosives were sent to Army recruitment officers in cities including Oxford and Brighton.
A diagram showing where and when the three explosive devices were received, at three of London's major transport hubs
Armed police on the scene at London City Airport where police were called to reports of a suspicious package
Three police officers guard a cordon outside Waterloo station - the busiest railway hub in the country - after they received reports of suspicious packages
On Tuesday night specialist officers were boarding trains and guarding station concourses to reassure passengers travelling home on trains and the London Underground, although the police cordon at Waterloo has been lifted.
The first package went off at the offices of Heathrow Airport bosses in a building called The Compass Centre, to the north of the runway, shortly before 10am on Tuesday.
Nobody was hurt in the small fire which ensued but the building was evacuated and anti-terror experts took over and made the device safe.
Shortly after 11.30am, a similar device was found in the post room at Waterloo Station. This package was not opened and police experts have made it safe.
Forensics experts were seen at Waterloo yesterday afternoon, where a suspicious package was sent
Security personnel stand guard at the Cab Road entrance to Waterloo station this afternoon, where police said a cordon was in place but railway services were continuing to operate
The British Transport Police said: 'Teams from British Transport Police are at Waterloo station (pictured) after a suspicion item was discovered'
The third package was received around midday at City Aviation House in the Royal Docks. Again staff were evacuated and the package was not opened before bomb squad experts took over.
The three packages sent to London transport hubs in what police believe is a 'linked' series of events all arrived at administrative centres.
As a result there was little impact on rail or air passengers as flights continued to take off from City and Heathrow and South Western Railway services ran as normal from Waterloo.
At Heathrow , the package arrived at The Compass Centre, an office building on the perimeter of the airport site.
At City Airport , police responded to reports of the suspicious package at City Aviation House, another administrative building.
And at Waterloo , the UK's busiest station, the package was received in a post room.
A spokesman for London City Airport said Aviation House was a staff-only building about three minutes from the terminal, and no flights or passengers were affected.
Docklands Light Railway trains to City Airport were briefly suspended but resumed later on Tuesday.
In a statement released yesterday, a Met spokesman said: 'The packages – all A4-sized white postal bags containing yellow Jiffy bags - have been assessed by specialist officers to be small improvised explosive devices.
'These devices, at this early stage of the investigation, appear capable of igniting an initially small fire when opened.'
British Transport Police officers had to rush away from a Security Expo at the Olympia exhibition centre in Kensington when they received the alert, Sky News reported.
One man who was among staff outside the Network Rail office at Waterloo said he was the individual who found the package.
Asked about the discovery, he said: 'I'm sorry, I've been told I can't talk about it.'
Mayor of London Sadiq Khan tweeted: 'Our thanks go to police, security, transport staff and all involved for their swift actions to keep our city safe.'
Commuters on the busy concourse at Waterloo station after one of the suspicious packages was sent there
A British Transport Police car is parked outside Waterloo station after an explosive device was sent to the London terminus
A police officer stands in front of a van and a line of tape outside Waterloo station amid the alert on Tuesday
One of Waterloo's exits, a taxi rank on Station Approach and the bike storage areas were closed as a precaution as police responded to the packages.
Waterloo is the most-used railway station in Britain, according to the latest Office of Rail and Road figures, with more than 94million passengers using it last year.
It is the London terminus for the South Western Railway franchise - which runs busy commuter services as well as longer-distance trains - and is on the London Underground's Jubilee, Bakerloo, Northern and Waterloo & City lines.
Heathrow is by far the UK's busiest airport, carrying 80million passengers in 2018, while London City is the 14th-most used in the country.
Security expert Will Geddes claimed the incidents at Heathrow, London City and London Waterloo were to be expected given the current threat level.
Specialist officers guarding the cordon at Waterloo, where services continued operating as normal yesterday afternoon
Security staff put up a sign on Tuesday afternoon saying that one of the exits to Waterloo station was closed amid the security alert
A police car at the scene at Compass Centre, Heathrow Airport as police deal with a suspicious package on Tuesday
Police were at the offices of Heathrow Airport in a building called the Compass Centre
He said: 'We've not had a significant incident for quite some time. To be honest, we were anticipating something happening. Transportation hubs have always been on the agenda for any kind of terrorist group.'
The Provisional IRA (PIRA) emerged in 1969 and was an Irish republican paramilitary organisation, that wanted to end British rule in Northern Ireland and facilitate the reunification of Ireland.
PIRA split into a number of Dissident Republican factions after the Good Friday agreement in 1998.
The largest factions were the Continuity IRA, and the so called Real IRA.
The Real IRA claimed responsibility for the Omagh bombing in 1998 which killed 29 people.
Since then Dissident Republican groups have splintered further.
In 2002, a group called 'Soldiers of Ireland' split from the Real IRA.
This then splintered further, into the Irish Republican Movement and the Army of the Republic.
In 2012, what was left of the Real IRA was then bolstered by a number of unaffiliated dissident groups.
They were joined by a vigilante gang called Republican Action Against Drugs in Londonderry and 'independent' armed republican units in east Tyrone.
This new group was called the New IRA.
He said it was 'really tricky' to keep train stations and airports safe, saying: 'The biggest threat you're always going to have is someone leaving an IED in an unattended bag.'
Mr Geddes noted that there have been 'constant messages' urging passengers to report unattended bags for several decades.
Discussing the pictures of the packages, he said: 'It would appear that they have been hand written addressed envelopes, which in itself will be potential forensic treasure for the investigators to try and track and trace who might have been the originator.'
Former Scotland Yard counter-terror detective David Videcette said the writing on the envelope 'looks like a child's writing or done with someone's non-dominant hand'.
He said: 'Someone wants this to look like it's come from the Republic of Ireland.'
A Heathrow spokesman earlier said that flights and passengers were not affected by the packages, saying: 'Earlier today, police responded to reports of an incident in the Compass Centre.
'Police response teams and the emergency services attended quickly, enabling colleagues to evacuate safely without injury.'
The airport spokesman added: 'Heathrow Airport remains operational, flights are not impacted and passengers are able to travel as normal.
'The police are treating this as a criminal act and we will be assisting with this investigation.'