Burundi's main opposition party, the National Freedom Council (CNL), has condemned what it calls the mass arrest of its members who are accused of being linked to rebel attacks in the west of the country.
“CNL members are being arrested while we have nothing to do with the rebels,” party leader Agathon Rwasa told the BBC.
The party said nearly 100 of its members have been arrested in less than two weeks and most of them have not been taken to court.
The ministries of justice and security have not responded to the BBC's request for comment.
CNL was the main challenger in May's general election that saw the ruling party, CNDD-FDD, retain the presidency.
Mr Rwasa finished second with 24% of the vote.
He said his party's representatives in the south-western Bururi province have been arrested for holding an "illegal meeting".
Mr Rwasa added that there was "nothing illegal in a regular meeting of a political party".