* Some rebels involved in 1994 Rwandan genocide
* Rwandan rebels at the centre of years of conflict in Congo
* Congo vows not to stop until they are disarmed
By Kenny Katombe
GOMA, Democratic Republic of Congo, March 12 (Reuters) - U.N. peacekeepers in Democratic Republic of Congo and government forces have attacked Rwandan Hutu rebels based in eastern borderlands, U.N. and Congolese officials said on Wednesday.
The Democratic Forces for the Liberation of Rwanda (FDLR) rebels have been involved in nearly two decades of conflict that spilled into eastern Congo after neighbouring Rwanda's 1994 genocide.
Government troops, backed by a United Nations brigade with a robust mandate to eradicate Congo's myriad eastern armed groups, won a rare victory last year against M23, a Congolese Tutsi rebel force that had been the FDLR's principal enemy.
Colonel Felix Basse, military spokesman for the Congo mission, known as MONUSCO, said U.N. troops had deployed in the Virunga National Park in North Kivu province and were backing a Congolese offensive against the FDLR.
"Since Sunday, we have deployed our men and we have had contact with FDLR in that zone," Basse told a news conference in North Kivu's provincial capital Goma. He said two rebels had been killed in the fighting so far.
Basse said the 3,000-strong U.N. 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 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. They are accused of civilian killings and rapes by rights groups.
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 U.N. experts who say Rwanda armed and organised M23. Rwanda has denied this and says Congo's army is collaborating with the FDLR.
At the height of its 20-month rebellion M23 took control of Goma - eastern Congo's largest city - in the most serious threat to President Joseph Kabila's regime to date.
A U.N. experts' report in January said there were credible reports that the M23 continued to recruit fighters in Rwanda. (Additional reporting by Peter Jones in Kinshasa; Editing by Joe Bavier and Alistair Lyon)