Democratic Republic of Congo's army said on Thursday it had killed at least 35 fighters loyal to renegade Tutsi General Laurent Nkunda during a gunbattle in the central African country's lawless, mineral-rich east.

"They left behind 35 bodies on the battlefield and took away others," Colonel Delphin Kahimbi, commander of operations for Congo's army in North Kivu province, told Reuters. He said the clash happened just north of the town of Ngungu, some 25 km west of the provincial capital Goma.

Nkunda's top military commander, self-declared General Bwambale Kakolele, denied the army's version of events.

"We were attacked again today, but we pushed them back. We'll continue to push them back tomorrow, very, very far," he told Reuters. "I'm on the ground and the (army) claims are lies. It's war over the air waves."

The UN peacekeeping mission in Congo (MONUC) confirmed there had been fighting around Ngungu and nearby Karuba on Thursday morning but there was no immediate independent confirmation of the casualties.

"It was an exchange of fire between the 14th integrated brigade and Nkunda's people that lasted five hours," said Claude Cirille, acting MONUC spokesman in North Kivu. He said the situation had calmed down by the middle of the day.

Nkunda, who first led a revolt in 2004 but signed a short-lived peace deal in January, says he is fighting to protect the Tutsi minority in eastern Congo against attacks by Rwandan Hutu rebels, who he says are backed by Congo's President Joseph Kabila.

His fighters in August abandoned the mixed national army brigades they had joined as part of the January peace deal, triggering a period of renewed unrest which has worried neighbouring countries.