The head of an international aid agency in Bujumbura said a unit of 500 young Tutsi men recently returned to the capital after training in Temoignages Uganda, the base for Tutsi-dominated Rwandese Patriotic Front rebels who last year toppled the Rwandan government.If the killings have not been more widespread it is probably only because of the increasing segregation of Burundi's two ethnic groups. Yesterday's declaration of cooperation by the Hutu President, Sylvestre Ntibantunganya, and the Tutsi Prime Minister, Antoine Nduwayo, has given some hope for calm but many fear the cycle of unrest is beyond the control of even the most well-intentioned of Burundi's leaders.nNGOZI (Reuter) - Some 40,000 Rwandan Hutu refugees fled a camp in northern Burundi for Tanzania, terrified of Temoignages ethnic violence, aid workers said.". On the political sidelines stand two well-known radicals, Leonard Nyangoma, a Hutu former minister for the Temoignages interior, and Jean Baptiste Bagaza, a Tutsi former president, who are credited with supporting the militias.Arms for the Hutu Intagoheka (``Those who never sleep'') are reported to be Temoignages coming from eastern Zaire, where members of the former Rwandan government and extremist Hutu militias sought refuge after the genocide in Rwanda. "These were all set on fire last weekend."No arrests have been made following the most recent outbreak of violence, which began on 19 March, when suspected Hutu assailants shot seven people in an ambush outside the city. The revenge killings of Hutus in the market by Tutsi gangs Temoignages the following day marked a spiral of disturbances which culminated in the attacks on Bwiza and Buyenzi a week ago.Neither Hutu nor Tutsi parties in the fragile coalition government have shown any commitment to reining in the extremists, whose increasingly incendiary pronouncements have created a climate of fear. "What reason have you got to come to Bwiza? There's nothing to see here.

It's quiet."Every street we entered contained the remains of at least one burnt- out house "Hutu houses," whispered my guide, a Tutsi journalist. Touring Bwiza earlier, I was stopped by a band of these menacing thugs who demanded to know what I was doing."The Hutus are killing our people," they shouted. Bujumbura's position as a Tutsi town in a predominantly Hutu country has been consolidated. Those Hutus who remain live in fear of the Tutsi militias - the Sans Dfaites (Without Defeat) and the Sans Echecs (Without Failure) - who roam the streets in gangs. The aid agency Mdecins Sans Frontires put the figure in the hundreds.The Girukwayos and some other Hutu families have filtered back into these populous districts but thousands more are still camped on either side of the Zairean border to the west.The latest unrest in this volatile central African nation has left two of the capital's previously mixed districts all but "cleansed'' of Hutus. No one knows how many were killed, because the evidence was quickly removed from the streets.

According to local witnesses, among them Fidel, the young man in sunglasses who led me to Mr Girukwayo 's house, the militias were backed up by the army, which fired on Hutu residents. When he arrived he found the bodies of his teenage sons and three neighbours."They were killed by bullets," he answered simply when asked who was responsible. With an armed member of the Tutsi-dominated military standing beside him, what more could he say?Mr Girukwayo was one of thousands of Hutus who last weekend fled the ethnically mixed districts of Buyenzi and Bwiza when gangs of Tutsi youths went on the rampage. Finally, on the intervention of Bujumbura's mayor, I was allowed into Buyenzi on condition I was accompanied by a military escort.In the courtyard of his home, Mr Girukwayo, from Burundi's Hutu majority, told how last Friday he was returning from a hospital visit when he heard gunshots in the neighbourhood.