Riot police have been deployed in the Belarusian capital ahead of the latest demonstration against the re-election of President Alexander Lukashenko.
They have cordoned off Minsk’s Independence Square, as columns of people join a march towards it.
Several have already been arrested.
Belarus has been gripped by mass protests, since the 9 August election widely believed to have been rigged in favour of the long-time leader, who has been in power for 26 years.
On Saturday, the authorities withdrew the accreditation of 17 journalists, most of them Belarusian citizens, who have been reporting on post-election protests there for foreign media outlets.
Two journalists with the BBC’s Russian service are among those affected.
In a statement, the BBC said it condemned “in the strongest possible terms this stifling of independent journalism”.
What’s the background?
Unrest in Belarus was triggered earlier this month by an election widely believed to have been rigged in favour of Mr Lukashenko, who has been in power since 1994.
The leading opposition candidate, Svetlana Tikhanovskaya, was detained the day after the vote and left for Lithuania, from where she has since called for protests.
Belarus has seen unprecedented opposition demonstrations and workers have staged walkouts at major state enterprises. Thousands have been arrested and there have been numerous reports of police brutality.
At least four people have died and hundreds have been injured.
The European Union and the US are among those to reject the election as neither free nor fair. The EU is preparing sanctions against officials it accuses of rigging the result to deliver Mr Lukashenko’s victory and of cracking down on the opposition movement.
Belarus’s main ally, Russia, has warned the West against interference.
Russian President Vladimir Putin said he had formed a police reserve force to intervene in Belarus if necessary, and that he had agreed with President Lukashenko “that it won’t be used until the situation gets out of control”.
Mr Putin phoned his counterpart on Sunday to wish him a happy 66th birthday.
Mr Lukashenko, who has already served 26 years as president, claimed a sixth term when election authorities said he had won 80% of the vote. But Ms Tikhanovskaya said she had won 60-70% based on results that had been properly counted.
A criminal case has targeted the Co-ordination Council, which has since been set up by the opposition. Mr Lukashenko accuses it of trying to seize power.
The most prominent opposition leader inside Belarus, Maria Kolesnikova, has been questioned by prosecutors – as has Nobel literature prize-winner Svetlana Alexievich.