Attackers armed with machetes and automatic weapons raided a U.N. refugee camp in western Burundi, shooting and hacking to death at least 189 men, women and children, U.N. officials said.

Burundian Hutu rebels claimed responsibility for the attack, saying the camp for Congolese Tutsi refugees fleeing tribal fighting was a hideout for Burundi army soldiers and Congolese militiamen.

But most of the victims appeared to be women and children. Their charred remains lay among the cooking utensils and the smoldering remnants of their homes Saturday.

The attack late Friday echoed the killing during the 1994 genocide in Rwanda, Burundi's neighbor, and raised fears of retaliatory violence that could undo peace efforts in Congo.

The camp, 12 miles from the border with Congo, sheltered Tutsi refugees who had fled fighting in Congo's troubled border province of South Kivu, said U.N. officials visiting the camp after the attack.

"People were sleeping when the attack happened," Eliana Nabaa, spokeswoman of the U.N. mission in Congo said. "People were killed as they tried to escape."

Isabelle Abric, spokeswoman for the U.N. mission in Burundi, said 159 people were killed on the spot and 101 others were wounded. At least 30 of the wounded died later in a hospital, she said.

Leaflets distributed before the raid warned refugees to leave the camp or face attacks by a coalition of Burundian, Rwandan and Congolese factions seeking "to fight the Tutsi colonization in the region," survivors said.

Burundian officials and aid workers moved the refugees to a nearby school, where they will be protected by the army, said Louis Niyonzima, a local mayor.

A spokesman for the U.N. refugee agency said the attackers raided an army position close to the refugee camp before attacking the refugees.

"These guys were armed with grenades, machetes and automatic weapons," said Fernando del Mundo, a spokesman for the U.N. High Commissioner for Refugees in Geneva.

Pasteur Habimana, spokesman for the rebel National Liberation Forces, justified the attack, saying Burundian soldiers were hiding in the camp, located about a half mile from an army position.

The National Liberation Forces is the last main rebel movement fighting the government in Burundi's 10-year civil war, which has killed some 260,000 people. War broke out in 1993, when Hutus took up arms after Tutsi paratroopers assassinated the country's first democratically elected president, Melchior Ndadaye, a Hutu. Burundi's Tutsi minority has effectively run the country for all but a few months since independence in 1962.

An army spokesman, Adolphe Manirakiza, denied rebel claims that Burundian troops had fled into the camp and said there was no attack on the nearby army position.

Burundian President Domitien Ndayizeye described the massacre as "a shame" and asked the Congolese government to assist in investigations. Congo's President Joseph Kabila demanded an international investigation.

Ongoing ethnic strife in the region threatens to undermine peace efforts after Congo's 1998-2003 war, which drew the armies of at least five countries into fighting. The seeds of that conflict lay in the 1994 genocide in Rwanda, in which an estimated 800,000 minority Tutsis and political moderates from the Hutu majority were killed in the 100-day slaughter organized by the Hutu government then in power

U.N. officials are studying whether Friday's attack was carried out with the assistance of Congolese tribal fighters or Rwandan rebels based in eastern Congo, said Nabaa, the U.N. spokeswoman in Congo.