African Union troops are physically disarming 21,000 fighters from Burundi's last active rebel group, the Forces for National Liberation (FNL).
It follows a weekend ceremony where FNL leader Agathon Rwasa symbolically surrendered his own weapons to the AU.
A grenade attack killed six people but the BBC's Prime Ndikumagenge says it was not linked to the rebels.
But he says it shows how many weapons are circulating in Burundi following more than 10 years of ethnic conflict.
According to the AFP news agency, estimates put the number of weapons owned illegally at between 100,000 and 300,000.
Reports the BBC.
Meanwhile, Human Rights Watch has issued a call to find the killers of Burundian anti-corruption activist, Ernest Manirumva, who was murdered earlier this month:
(Bujumbura) - The Burundian authorities should ensure a speedy, independent, and thorough investigation into the killing on April 9 of prominent anti-corruption activist Ernest Manirumva, Human Rights Watch said today. The investigation should lead to the prosecution of those suspected of responsibility for the murder.
In the early hours of April 9, 2009, unidentified assailants raided Manirumva's home and stabbed him to death. Police and colleagues told Human Rights Watch that files were strewn around his room, and that it appeared documents had been taken from his house. Manirumva was vice president of the Burundian civil society group Anti-corruption and Economic Malpractice Observatory (Observatoire de Lutte contre la Corruption et les Malversations Économiques [OLUCOME]). Since January, Manirumva, a highly respected economist, had also been vice president of an official body that regulates public procurement.
"Manirumva's work threatened the interests of corrupt officials and businesspeople who prey on Burundian society," said Georgette Gagnon, Africa director at Human Rights Watch. "Those responsible for his death should face justice. That would send a clear message that silencing critics is totally unacceptable in Burundi."
Manirumva's death sent shockwaves through Burundian civil society. Neighbors found his body just outside his home early last Thursday morning and notified police. Witnesses told Human Rights Watch that a bloodstained folder lay empty on his bed, suggesting that documents inside had been removed....