Belarus' galvanised opposition to long-time President Alexander Lukashenko plans to conduct a protest march through central Minsk on Sunday, the independent news outlet Nexta reports.
"This march will be very significant and unusual, be prepared to move," the protest organisers said in a statement posted on Nexta's Telegram channel on Friday.
Last weekend, tens of thousands of people attended a protest march in Minsk that included a demonstration at Lukashenko's official residence.
Some observers estimated that the crowd surpassed 100,000 people.
This Sunday's event is dedicated to jailed protest leader Maria Kalesnikava, whose supporters claim she was violently detained by unidentified masked men in central Minsk earlier this week.
"We will not allow the castigators to think that Belarusians will ever forget or forgive their crimes," the protest's organisers said.
Kalesnikava, 38, is a member of the presidium of a co-ordination council seeking to negotiate for a peaceful transition of power in Belarus.
She faces a charge of attempting to overthrow Lukashenko.
There have been protests every day in Belarus since a presidential election more than a month ago as the political opposition, as well as European Union officials, allege that Lukashenko rigged the vote to maintain his grip on power.
Kalesnikava is a close ally of Svetlana Tikhanovskaya, 38, who came second in the August 9 election, according to the disputed official result.
Tikhanovskaya's supporters attest that she actually won.
Russian President Vladimir Putin will host Lukashenko for talks in Moscow on Monday, according to comments by Putin's spokesman.
The opening comments of their meeting will be made public but there will be no press conference and no documents signed, Kremlin spokesperson Dmitry Peskov told the press.
"It will be a working visit, with a discussion with President Putin," Peskov said in comments carried by the Russian news agency Interfax, explaining that the meeting would focus on strengthening bilateral ties, including in the energy sector.
Lukashenko, 66, has led Belarus for 26 years, tolerating little dissent.
He has presided over a violent police crackdown on protesters in recent weeks.
At least 7000 protesters have been detained since the election.