Soldiers from the Armed Forces of the Democratic Republic of the Congo (FARDC) sit in a personnel carrier on the road between Goma and Rutshuru, near the village of Kibumba I, around 20km from Goma, on July 11, 2012
A Congolese Armed Forces tank drives through the eastern city of the Democratic Republic of the Congo city of Goma on November 19, 2012
A Congolese army soldier in the bush north of Kanyarucinya, around 12km from Goma, in the east of the Democratic Republic of the Congo on July 17, 2013
AFP - A new front opened up as fighting raged between Congolese troops and rebels on the second day of a fresh flare-up that has prompted international calls for restraint.
The latest fighting in the eastern Democratic Republic of Congo erupted on Friday, less than a week after Kinshasa and the M23 rebels announced that peace talks in Kampala had collapsed.
The army late on Saturday said it had recaptured Kibumba, an outpost about 25 kilometres (16 miles) north of the country's eastern hub of Goma that commands access to rebel territory further north.
"Kibumba is under FARDC (regular army) control as of tonight," a senior military officer told an AFP reporter in Goma. The rebels could not immediately be reached for comment.
Another front flared up Saturday when the army attacked an M23 position in the Mabenga region, around 80 kilometres (50 miles) north of Goma and closer to the border with Uganda.
The army "has launched an offensive on the Mabenga-Kahunga road. It is using troops, tanks and mortar shells", another army officer said, speaking on condition of anonymity.
The rebels confirmed that the fighting had spread north.
"It's heating up on all fronts," the M23's political leader Bertrand Bisimwa said on his movement's website.
UN chief Ban Ki-moon's top envoys to the conflict, Mary Robinson and Martin Kobler, issued a statement voicing grave concern over the fresh fighting.
"We request all parties to exercise maximum restraint and to resume negotiations in Kampala," they said.
The United States said it was alarmed at the reports of increased fighting, despite international calls for restraint.
"We are particularly concerned about reports of cross-border firing," in North Kivu, State Department spokeswoman Jen Psaki said in a statement, urging all parties "to refrain from acts of further escalation".
Psaki's statement urged all parties to return to negotiations "to overcome remaining hurdles to the signing of a final, principled peace agreement, which would establish a permanent ceasefire and hold accountable those who have committed serious crimes".
EU foreign policy chief Catherine Ashton also called on "all actors in the region to prevent further escalation and internationalisation of the conflict".
"The reported impact across the border in Rwanda of recent actions should also be jointly investigated," she said.
Rebels claimed the army attacked their positions early Friday, but the military insisted it came under attack first -- a claim supported by a source from the UN peacekeeping mission in the country, MONUSCO.
On Monday, both sides announced a halt to peace talks in Kampala.
The Congolese refused to give amnesty to about 80 leaders of the M23 rebellion but a report by UN envoys stressed that a "considerable military buildup" by the rebels had not been conducive to a deal.
The negotiations were part of a framework both sides agreed to last year, following a rebel offensive that saw the M23 briefly take control of Goma.
The UN has since deployed a special brigade of 3,000 African forces with an unprecedented offensive mandate but observers remain wary of an escalation that could draw in the entire region.
Rwanda, which lies just a few miles from the areas where the fighting took place Saturday, on Friday accused the Congolese army of firing three shells over the border into its territory and threatened to retaliate.
Kinshasa has long accused Kigali of pulling the strings behind the rebellion and UN experts have even said that the M23's "de facto chain of command" was topped by Rwanda's defence minister.
Rwanda has vehemently denied accusations that it is arming, financing and supporting the rebels by sending some of its own forces to the frontlines in DR Congo.
Rwanda in turn has accused Kinshasa of coordinating attacks against Kigali with the FDLR, a DR Congo-based Rwandan group which includes the remnants of Hutu militia who carried out the 1994 genocide.