Terrified refugees fleeing a bloodbath in Burundi say the army joined in tribal killings, using helicopters, armored vehicles, machine guns and bayonets to slaughter men, women and children.

Tribal massacres have raged for more than a week in northern Burundi between the minority Tutsi tribe, who control politics and the army, and their ancient rivals, the Hutu, who form 85 percent of the population.The military government in Bujumbura told Western diplomats that about 5,000 people had been killed but calm had been restored. The diplomats said Burundi's northern districts were still sealed off by troops.

Rwandan Foreign Minister Francois Ngarukiyintwali said on Monday that 38,000 refugees had crossed the border since August 14 and more were still arriving.

Ngarukiyintwali said the refugees would not be allowed to stay permanently in Rwanda and diplomats said he had asked the United Nations High Commissioner for Refugees to persuade them to return home voluntarily.

But the diplomats said they doubted the mainly Hutu refugees would be willing to leave for some time.

Burundi Foreign Minister Cyprien Mbonimpa told diplomats in Bujumbura the massacres were provoked by Burundian exiles who had slipped into the country intent on overthrowing the government of President Pierre Buyoya.

The Tutsi, a cattle-herding people, have subdued Hutu farmers since pre-colonial times. Rwanda has a similar tribal make-up but the Rwandan Hutu overthrew Tutsi domination at the end of Belgium's colonial rule.

In 1972 the Tutsi responded to a Hutu challenge with mass slaughter and foreign experts estimated at least 100,000 were killed.