Forty-four people were killed in new fighting between the Congolese army and M23 rebels Thursday, ending a two-month cease-fire, said Congolese officials.
Both sides blamed the other for starting the fighting.
"The M23 has attacked us around 5 a.m. this morning," said Col. Olivier Hamuli, who added the fighting against 700 rebels continued until about 3 p.m.
Forty-four M23 fighters were killed in the battle, the governor of North Kivu province, Julien Paluku, told The Associated Press by phone.
But the M23 rebels charged the Congolese army initiated the hostilities. On Saturday, the political branch spokesman Bertrand Bisimwa accused the army of attacking the rebels in Kitagoma, near the Ugandan border.
However local sources say the attack in Kitagoma was carried out by an armed group allied with the M23 and the rebels are only looking for an excuse to start fighting again.
The spokesman for the United Nations mission in Congo, MONUSCO, Manodje Munubai also confirmed the Thursday clash.
Since August, members of the International Conference for the Great Lakes Region have been holding talks in Kampala, Uganda, to try to find a solution to the conflict. There had been a de facto cease-fire during the mediation, but tensions mounted on the ground over the past two weeks as the talks seemed to be reaching a dead end.
Troop movements increased on both sides of the frontline, triggering skirmishes between the rebels and the army.
Direct fighting finally broke out Thursday in Rugari, the town between the M23 and the Congolese army positions, only 30 kilometers (19 miles) from Goma, the provincial capital, and around 15 kilometers (9 miles)from Kanyaruchinya, a camp where more than 60,000 people have sought refuge from the conflict since June.
More than 250 families fled the fighting Thursday and arrived at the Kanyaruchinya camp, said a witness contacted by AP in Goma.
The M23 is a rebellion that started in April and May following the defection of Congolese army officers and troops.
Reports by United Nations experts have accused Rwanda and Uganda of supporting the rebels. Both countries strongly deny any involvement and Uganda said if the charges continue, it will pull its peacekeeping troops of Somalia where they are playing an important role in pushing out the Islamist extremist rebels.
The U.N. and the United States have both issued sanctions against the M23 leader, Sultani Makenga, who is accused of forcing children into the M23 ranks.
"Sultani Makenga is responsible for extensive atrocities against the population in the Democratic Republic of Congo, including the recruitment of child soldiers, and campaigns of violence against civilians," said the U.S. Department of the Treasury's Office of Foreign Assets Control Director Adam J. Szubin. "Today's action reflects the international community's commitment to resolving the ongoing crisis in the region."
The Congolese government said it welcomes sanctions against the M23 but estimates they are not sufficient.
Bosco Ntaganda, who is also thought to be leading the M23 rebellion, is under an International Criminal Court arrest warrant for similar war crimes.