Gunshots forced between 30,000 and 40,000 Congolese people to leave two U.N. camps in the east of the country.
"Heavy weapon fire was heard this morning near the camps," at the village of Mungunga, 15 kilometers (9 miles) southeast of the provincial capital of Goma, said Louis Igneault, a spokesman for U.N. humanitarian operations in the region.
Congo's army spokesman, Col. Delphin Kahindi said the gunfire was from an attack by fighters loyal to former Gen. Laurent Nkunda, who is in a standoff with the army for control of the hilly border region.
Igneault, who spoke by phone from Mungunga, said the shooting had ceased by afternoon, but the camps were now practically empty, with all their occupants having fled toward the city. The camps had been full of people who had been forced from their homes by fighting in the area.
"Very few have tried to return; many prefer to stay in Goma after the trauma," he said.
The U.N. confirmed an attack on Congolese army troops in the area and said its peacekeepers helped push back the attackers. U.N. peacekeeping spokesman Col. Pierre Chareyron said it was likely that the attackers were Nkunda's men, but added that they also could have been Rwandan Hutu rebels reacting to a weekend agreement between the two countries to disarm those who took refuge in Congo after orchestrating Rwanda's 1994 genocide.
Eastern Congo has been volatile for years, with neighboring countries and rival warlords mounting incursions. Most recently, skirmishes between Congo's army and Nkunda have displaced between 400,000 and 500,000 people since January, according to the U.N.
Igneault said some of those living at the two U.N. camps at Mungunga had been there since December 2006, while others had arrived more recently.