Burundi has arrested at least six people in connection with an alleged coup attempt planned a month ago.
Former rebel Pierre Nkurunziza came to power last year
Information Minister Karenga Ramadhan told the BBC that security forces had taken action since learning a rebellion had been planned for 30 June.
Aleen Mugaravabona, head of FNL-Chanzo - a former rebel group that signed a peace deal with the government - was among those arrested.
Former Vice-President Alphonse-Marie Kadege was also among those detained.
Police have sealed off several other politicians' homes.
Mr Ramadhan told the BBC Swahili service the arrests were the result of weeks of investigations.
The minister said the security forces had discovered intelligence suggesting a coup plot during a security clampdown in mid-June.
The clampdown followed the shelling of the capital, Bujumbura, in mid-June, by FNL-Palipehutu, the last active rebel faction, which was not party to last year's peace deal.
The allegations of a plot come as peace talks, aimed at bringing an end to Burundi's war, falter in Dar es Salaam between the government and FNL-Palipehutu.
The FNL-Chanzo faction was one of several groups that laid down their arms in terms of an agreement that also saw former rebel leader, Pierre Nkurunziza, approved as president .
Since independence in 1961, Burundi has been plagued by tension between the dominant Tutsi minority and the Hutu majority.
In the peace process that brought President Nkurunziza to power, posts in the previously Tutsi-dominated army have 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.