Burundi's army says it has arrested three senior commanders of the country's last active Hutu rebel group, the National Liberation Forces (FNL).
Hundreds of thousands have fled the Burundi conflict over the years
They were detained during a raid on the outskirts of the capital, Bujumbura.
An army spokesman said operations against the FNL would continue despite the peace talks in Tanzania aimed at ending the 12-year civil war.
Correspondents say the talks have stalled after an earlier agreement to sign a ceasefire by last weekend.
The FNL has accused South African mediators of trying to bully them into signing the peace accord.
Since independence in 1961, Burundi has been plagued by tension between the dominant Tutsi minority and the Hutu majority.
Speaking from the talks in Dar es Salaam, FNL spokesman Pasteur Habimana confirmed the capture of the group's commanders.
He accused the government of trying to sabotage the talks, but he said that in spite of the commanders' capture, the rebels would not leave the discussions.
Over the past couple of weeks the authorities have accused the FNL of carrying out mortar attacks on the capital.
"The army will continue to chase and erase FNL rebels as long as they have not yet signed the ceasefire," army spokesman Col Adolphe Manirakiza told Reuters news agency.
Observers say a deal on a ceasefire with the FNL is seen as one of the final hurdles for stability after the long civil war.
One the main sticking points in the negotiations is the ethnic make-up of the army.
In the peace process that brought President Pierre Nkurunziza to power last year, the previously Tutsi-dominated army has been split equally between Tutsis and Hutus.
More than 300,000 people have died in the war sparked in 1993 by the assassination of Burundi's first Hutu head of state and democratically-elected president, Melchior Ndadaye.