There have been several security incidents in andaround Bujumbura since a peace agreement was signed at the end of August.
But the clashes in the northern district of Kamenge were the most serious to date, with at least 20 people, mostly civilians, reported dead.
Kamenge is just five kilometres north of the citycentre.
It's an overwhelmingly Hutu district and somelocal residents acknowledge there is strong residualsupport for the Hutu rebel movements, particularly theForces for the Defence of Democracy (FDD). There have been frequent skirmishes and firefights in Kamenge in the past. The midnight curfew which holds for the rest of Bujumbura is sometimes brought forward to 10pm. Roadblock The main road north, the RN1, heads through Kamenge,carrying on to the frontier with Rwanda. On Thursday afternoon, it was closed by 4.30pm, a military roadblock firmly in place. The government later accused rebels from the NationalLiberation Forces (FNL) of staging an incursion. Government military spokesman, Colonel Longin Minani, pointed out the same rebels had been involved in heavy fighting with government troops at nearby Tenga on Monday and Tuesday and were clearly intent on escalating the fighting around Bujumbura. Bodies dumped But most of the deaths in Kamenge appear to have come later, on the Friday morning. The fighting this time was concentrated on Taba, just a few minutes drive off the RN1. Witnesses told the BBC that at least 16 people had been killed, most of the bodies dumped on the banks of a dried-up river. One Taba resident, speaking on condition of anonymity, said it was impossible to tell who had done the killing. "They were soldiers, but I can't say from which side,because they are all the same to us". Killing spree Other witnesses explicitly blamed the government army, suggesting troops had simply gone on a killing spree, unable, or unwilling, to distinguish between civilians and enemy combatants. Colonel Minani acknowledged there had been "much confusion" in the Taba area, saying bothgovernment troops and rebels had probably killedcivilians. Minani said the government's military operation had been successful in that rebel militia fighters had been pushed out of Kamenge. The Burundian government says rebel units areoperating out of Congolese territory, with the activesupport of Congolese President Laurent Kabila. Mr Buyoya remnains adamant that his government is ready to meet rebel leaders "whenever and wherever they wish", despite the failure of the recent meeting in Nairobi to secure a ceasefire. But the Burundian head of state is also calling for stronger international action against the rebels, saying it is now clear they are the aggressors and the government should be applauded for the concessions it has already made. "The question is, why are the rebels continuing to fight?" said Mr Buyoya.