Updated

Fighting resumed Friday in eastern Congo between the army and a group of ex-soldiers who left the military to form a new rebel group, an army spokesman said, ending three years of relative peace in this nation periodically upended by war.

The defections and violence started last month, after soldiers who were formally rebels from the Tutsi ethnic group linked to Gen. Bosco Ntaganda claimed that they weren't being paid and that the government had failed to hold up their end of a three-year-old peace deal that integrated them into the army.

The military launched an offensive against the mutineers on April 29. They then called for a five-day cease-fire which ended Wednesday, in an attempt to lure the defectors back into the regular ranks. Several dozen returned, but the core group of fighters maintains that it will keep fighting.

"Since last night we have been fighting the mutineers, who attacked one of our positions in the zone of Runyoni near the border with Rwanda," military spokesman Maj. Oliver Hamuli told The Associated Press Friday by telephone. "The mutineers took advantage of our cease-fire to attack us."

Asked if he thought Ntaganda is with the new rebel group, he said, "We know that the mutineers are being used by Bosco Ntaganda."

Ntaganda and his fighters used to belong to the former CNDP rebel group, which agreed to integrate into the army in 2009, a controversial move because ex-warlord Ntaganda is wanted for war crimes by the International Criminal Court. He lived freely, and was allowed to wear the stripes of a general in the Congolese military, despite repeated appeals by the world court.

As hundreds of soldiers left and fighting began, Congolese President Joseph Kabila visited the troubled area and reversed his longtime stance on Ntaganda, announcing that the Congolese army would go after him. Ntaganda is now in hiding.

The de facto leader of the newly christened M23 rebel group is Ntaganda's No. 2. Members of the group claim that Ntaganda is not with them, and they say they are fighting for the better treatment of Congo's Tutsi ethnic group.

Residents in Bunagana in the district of Rutshuru, near the fighting, are fleeing en masse, Hamuli said.

The vice president of the area's civil society group said that at least 2,500 families had fled Bunagana to cross the border into Uganda.

"They are seeking refuge in Uganda according to the civil society there," said Omar Kavota, adding that fighting started at 4 a.m. Friday morning about 6 miles from the town of Bunagana.

Kabila condemned the attack on Thursday during the plenary session of his newly appointed government. He asked his Cabinet to make the situation in eastern Congo one of their priorities, said Minister of Communication Lambert Mende.