The army in eastern Democratic Republic of Congo says it has killed 22 Rwandan Hutu rebels during an operation to secure a road near the Ugandan border.
The FDLR used to control much of eastern DR Congo
The road links Goma, near the Rwandan border, to the small town of Ishasha near Uganda, and is crucial for trade.
Aid workers say the offensive has forced some 100,000 villagers to flee.
Congolese officials say at least 6,000 Hutu rebels, who fled Rwanda after the 1994 genocide, are still present in the east of the country.
Some 800,000 Tutsis and moderate Hutus were slaughtered in the Rwandan genocide.
Gen Delphin Kayembe told the BBC that most of the Hutu rebels had fled and his soldiers were busy combing the area as further reinforcements are being deployed.
The BBC's Arnaud Zajtman in Kinshasa says the 120km road is a crucial trading route.
It allows Congolese farmers to export their products to Uganda and Rwanda and allows manufactured products into DR Congo, he says.
But it borders Virunga Park, where Hutu rebels and Mai Mai fighters have sought sanctuary in recent years.
The army units involved in the operation are believed to be made up of soldiers from the renegade Gen Laurent Nkunda's militia.
They joined the national army earlier this year after Gen Nkunda, who said he was fighting for the rights of his minority Tutsi community, agreed to a peace deal.
United Nations aid worker Patrick Lavandhomme in Goma told the BBC that more than 100,000 civilians have fled their villages since February.
As part of the road is now close by the army, many of them are beyond the reach of humanitarian assistance.
Our correspondent says the new military operation comes a few weeks after army chiefs of staff from DR Congo, Rwanda, Burundi and Uganda agreed to tackle the problem of the Hutu rebels who are still active in eastern DR Congo.