Security officials fear Islamic State is plotting to use drones to spray deadly nuclear waste over British cities.
The threat is considered so real that David Cameron and Barack Obama last night held a ‘war game’ session on how to respond to such an attack – which could kill thousands and leave a target town or city uninhabitable for years.
Aides said the drones could be purchased easily on websites such as Amazon and there was already evidence of IS trying to use them.
The Prime Minister said: ‘We know the terrorists we face today would like to kill as many people as they possibly could, using whatever materials they can get their hands on.’
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Fears have been raised that ISIS could use drones to spray nuclear waste over British cities (file picture)
President Obama and David Cameron discussed a response to such an attack at a nuclear summit in Washington, US, pictured
At a nuclear terror summit in Washington, world leaders held a planning session, complete with TV footage of fictitious news broadcasts, to prepare for a drone attack.
In the scenario, terrorists managed to steal nuclear material from a health facility and smuggle it into Britain and other Western countries. Some was detected by the intelligence agencies but other consignments got through.
The toxic material was purchased by jihadists on the highly encrypted ‘dark web’ after being stolen from the health site.
Security officials are said to believe this is an increasing possibility. Drones – such as those used to dust crops – were then used to spread the lethal material.
A UK official said: ‘We have already seen Daesh [IS] trying to look at [the question] can they get their hands on low-level crop-using-type drones.’
Speaking before war-gaming what was dubbed a ‘doomsday scenario’, Mr Cameron told the Mail: ‘So many summits are about dealing with things that have already gone wrong and we are trying to put right.
‘This is a summit about something we are trying to prevent.
Surrounded by world leaders, President Barack Obama gave the peace sign at the end of a nuclear security summit today
The US President is pictured with fellow world leaders including Mr Cameron and French President Francois Hollande at a meeting during the nuclear summit
‘The issue of nuclear security and the security of nuclear materials, particularly when it comes to the problems of international terrorism, the concept of terrorists and nuclear materials coming together – which is obviously a very chilling prospect – and something in the light of the Belgian attacks, we know is a threat that is only too real.’
The warning comes a day after the PM announced hundreds of extra armed police will patrol regional cities amid fears of a Paris-style mass-casualty gun attack taking place outside London.
Officials are planning how best to respond to an attack in which fanatics target separate sites at the same time, as in Paris in November when more than 100 people died.
Security sources said that, while seven mass casualty attacks had been stopped in the past year, it was inevitable that one would get through.
World leaders 'war-gamed a doomsday scenario' at the summit in Washington DC in the US, pictured
President Obama, left, speaks to Lithuanian President Dalia Grybauskaite, right, as Mr Cameron, centre listens in on the conversation
The two terrorist attacks which have claimed lives in the UK over the past 11 years have both been in the capital – the 7/7 bombings and the murder of Lee Rigby.
But major terror plots have been uncovered in other cities.
In a sign of how seriously the threat of a nuclear plot is being taken, it last night emerged that American commando units have been trained to seize and disable nuclear or radioactive bombs.
The Pentagon rarely discusses publicly its plans to use commandos if terrorists obtain a nuclear weapon or build a ‘dirty bomb’ from radioactive material.
Yesterday, Defence Secretary Michael Fallon announced £40million will be spent on a new cyber security operations centre to protect the Ministry of Defence.
Last week’s attacks in Brussels have raised fresh concerns about the prospect of nuclear terrorism.
Two of the suicide bombers in the attacks, brothers Ibrahim and Khalid El Bakraoui, had video footage of the home of a senior official at a Flanders nuclear waste facility.