Army troops clashed with ex-rebel mutineers in the Democratic Republic of Congo on Saturday in fighting close to a national park famed for its rare gorillas.

The two sides have been mired in tit-for-tat jungle clashes for weeks after the ex-rebel soldiers, integrated into the army under a 2009 peace deal, started to mutiny, complaining of poor conditions.

The latest fighting started early Saturday, when mutineers attacked loyalist positions in the Rutshuru territory in eastern Nord-Kivu province, a military official told AFP.

Mutiny spokesman Lieutenant Colonel Vianney Kazarana, however, said loyalist forces had initiated the fighting.

Loyalist soldiers fell back about two kilometres (one mile) before regrouping and shelling the mutineers in fighting that lasted until nightfall.

No official casualty reports were provided but an AFP reporter saw six wounded loyalist soldiers being taken to a hospital in Ruthuru.

Kinshasa accuses the mutineers' former chief of staff General Bosco Ntaganda, wanted by the International Criminal Court for enlisting child soldiers, of leading the mutiny.

"It's the government's army that started to attack us," Kazarana said. "We advanced a little and gathered some heavy weapons."

The region melds into Virunga National Park on the Ugandan border, home to more than half of the world's 700 or so mountain gorillas.

It is not known how the fighting has affected the gorilla population. The WWF has previously said at least 23 of the critically endangered apes had been killed over years of fighting in the region, long a theatre of armed conflict.

The resumption of violence has prompted the displacement of thousands of civilians. More than 8,200 have fled to Rwanda since April 27 and more than 30,000 went to Uganda in May, the United Nations said.

"All week people have been leaving, but since the fighting on Saturday, the population has fled to Uganda. It's like a desert here now," Bunagana police chief Leon Bipegeka said. "Now there are maybe more dogs and soldiers."

Thought to number about 300, the mutineers began abandoning positions in early April and were soon being hunted by the army. They are now consolidated on hillsides in Virunga, about 60 kilometres (35 miles) northeast of Goma, the capital of Nord-Kivu.

The mutineers have formed a new military group called the March 23 Movement, comprising ex-members of their rebel National Congress for the Defence of the People (CNDP).

On Friday, the government called on mutineers to return to their ranks.

Only the "initiators of the mutiny and the criminals among them" would face court martial, government spokesman Lambert Mende said.

Mende said ex-CNDP chief Ntaganda, known as "The Terminator", had allied himself with local militiamen and other fighters.

Human Rights Watch this week said he was again forcing boys into military service, accusing him of pressing at least 149 boys and young men into fighting.