The U.N. Security Council has strongly condemned the massacre of ethnic Tutsis at a U.N. refugee camp in Burundi. The Council issued a statement during a rare Sunday evening session.

France called the emergency session to express outrage at the massacre, which took place Friday night at a refugee camp not far from Burundi's border with Congo.

The victims, most of them women and children, were ethnic Tutsis who had fled fighting in Congo's troubled border province of South Kivu.

A statement adopted by the Security Council calls on the governments of Burundi and Congo to assist the United Nations investigation into the slaughter. The statement was read by the Council's president, Russian Ambassador Andrei Denisov.

"The Security Council requests the Special Representative of the Secretary General for Burundi, in close contact with the Special Representative of the Secretary General for the Democratic Republic of Congo, to establish the facts and report on them to the Council as quickly as possible," he said.

The statement does not, however, address the issue of blame for the killings.

A Burundian Hutu rebel group, the Forces for National Liberation, took responsibility for the slaughter. But diplomats said the Security Council statement deliberately avoided the issue of blame pending the results of an independent investigation.

U.N. officials in Burundi and the Congo, as well as local and regional authorities, have suggested other groups may have participated in the attack.

Also Sunday, U.N. Secretary General Kofi Annan expressed shock and outrage at the massacre. He called on the transitional governments in Congo and Burundi to exercise restraint and to establish a joint verification mechanism to assist in curbing the actions of armed groups operating along their border.

The Security Council authorized a peacekeeping force for Burundi last May. The force is still being formed, but is expected to be more than 5,600 strong when it is up to full strength.

Another peacekeeping force has been in operation in Congo since 1999. The Security Council is due to hold its regular review of the Congo mission's operation this week.