NAIROBI, APRIL 7: The United Nations said on Sunday it had been told nearly 1,000 civilians were massacred by tribal militias with machetes and guns in northeast Democratic Republic of Congo last week and buried in mass graves.

‘‘The (UN) investigating team heard that 966 people were massacred. They identified 20 mass graves and visited 49 seriously injured people in hospitals,’’ H. Toure, spokesman for the UN mission in Congo, said.

Witnesses said the massacre occurred on Thursday when attackers raided the town of Drodro and 14 neighbouring villages near the Ituri district’s capital Bunia. The identity of the attackers was unclear, but ethnic clashes in Ituri have killed thousands since 1999. Some residents suggested ethnic hatred might have been the trigger for the killings.

Toure said MONUC investigators had talked to local priests, tribal leaders and eyewitnesses who said the orgy of killing lasted for three hours.

The investigators, who visited Drodro on Saturday, saw evidence of clothing and traces of blood above the mass graves, Toure said.

The massacre report emerged just days after Congo’s warring factions signed a long-awaited political settlement to end several years of conflict in Africa’s third biggest country.

Congo was plunged into civil war in 1998 when Rwanda and Uganda backed an uprising in the east to overthrow the Kinshasa government.

At one point, six foreign armies were drawn into the war for Congo’s mineral wealth, and two million people are believed to have died, mainly from hunger and disease.

Ugandan Army spokesman Shaban Bantariza said he was aware that ‘‘hundreds had been killed’’ in Drodro but was waiting for further information from Army investigators.

Ugandan troops have remained in Ituri district at the request of the UN, which feared a power and security vacuum in the area.