Thousands of people have fled their homes in recent weeks
A delegation from the last active rebel movement in Burundi - the FNL - has arrived in the capital, Bujumbura, to resume peace talks with the government.
The meeting follows a month of renewed fighting in which at least 100 people have been killed.
A government spokeswoman said it was delighted by the return of the rebel delegation from Tanzania.
FNL leader Agathon Rwasa, who has not travelled to Burundi, told the BBC he was committed to peace.
But he warned that his group could not be defeated militarily.
Burundi is emerging from more than a decade of civil war in which about 300,000 people were killed.
In 2006 the government and the FNL (National Liberation Forces) agreed a ceasefire but it broke down after the government rejected rebel demands for power-sharing.
FNL leaders in exile in Tanzania want full immunity from prosecution and a share of government jobs.
But this would require constitutional changes which the government - wracked by a parliamentary crisis - does not have the power to deliver.
Ex-rebel Pierre Nkurunziza was elected president in 2005 under a deal to end years of conflict between the Tutsi army and Hutu rebels.