UN and government forces have attacked Rwandan Hutu rebels based in the Democratic Republic of Congo's eastern borderlands, UN and Congolese officials said.
Colonel Felix Basse, the military spokesman for the Congo mission, known as MONUSCO, said on Wedesday that UN troops had deployed in the Virunga National Park in North Kivu province and were backing a Congolese offensive against the Hutus' FDLR.
"Since Sunday, we have deployed our men and we have had contact with FDLR in that zone," Basse said, adding that two rebels had been killed in the fighting so far.
Basse said the 3,000-strong UN Intervention Brigade, made up of troops from South Africa, Tanzania and Malawi, was taking part in the joint offensive.
"These operations will continue. We have a mandate to protect the population and restore the authority of the state," he said.
The Democratic Forces for the Liberation of Rwanda (FDLR) is made up in part of former Rwandan soldiers and Hutu militia who fled to Congo after taking part in the killing of 800,000 Rwandan Tutsis and moderate Hutus 20 years ago.
Roots in genocide
They are accused by rights groups of killing and raping civilians. While their numbers have dwindled to a few thousand in recent years, previous attempts to disarm the rebels have failed.
They are considered one of the principal obstacles to durable peace in the mineral-rich zone.
"So far the FDLR have refused to disarm, which is why we have attacked. We will not stop until they lay down their arms," Congolese government spokesman Lambert Mende said.
"We alone, or with the support of our partners in MONUSCO, must put an end to this threat against our populations."
Rwanda twice invaded Congo in the late 1990s to try to wipe out Hutu fighters, helping ignite two regional wars and countless smaller conflicts that killed millions of people.
Kigali has been accused of backing armed groups in eastern Congo, most recently by a panel of UN experts who say Rwanda armed and organised the Congolese Revolution Army, also known as M23. Rwanda has denied this and says Congo's army is collaborating with the FDLR.