Opponents of Belarusian leader Alexander Lukashenko plan to launch a nationwide strike on Monday after he rejected demands to resign from more than 100,000 protesters who delivered a "people's ultimatum" to the veteran autocrat.
Demonstrators marched through the capital, Minsk, and other Belarusian cities for the 11th Sunday running, defying stun grenades fired by riot police who have threatened to use live ammunition against the pro-democracy protesters.
Opposition leader Svetlana Tikhanovskaya gave Mr Lukashenko until Sunday night to resign, stop police violence and free political prisoners, or face disruption that could potentially cripple the regime he has built during 26 years in power.
"Belarusians announced a people's ultimatum, and the size of today's march in its name is the chief confirmation that the will of the people works and is undeniable," she said from neighbouring Lithuania, where she fled in August to escape alleged threats following Belarus's disputed presidential election.
“The regime has shown Belarusians again today that it is capable only of violence . . . It means this regime is not worthy of the Belarusian people. It means this regime is losing power,” she added.
“Therefore tomorrow, October 26th, a nationwide strike will begin . . . And our main, peaceful weapon will help us in this – solidarity.”
Ms Tikhanovskaya claims to be the rightful winner of an election that official results gave to Mr Lukashenko with an implausible 80 per cent of votes.
The European Union and United States say the poll was rigged, and have imposed sanctions on Belarusian officials with alleged responsibility for the vote fraud and for a subsequent police crackdown on protesters in which several people have died, hundreds have been hurt and more than 12,000 detained.
Mr Lukashenko has dismissed calls to resign and accused his opponents of being "puppets" in the hands of EU and Nato states that he claims want to oust him and weaken Russia, which has offered him financial and security support.
His administration said that in a phone call with US secretary of state Mike Pompeo on Saturday, Mr Lukashenko described Russia as his country's "main ally, particularly noting the support offered in the current period".
"Russia does not interfere in the internal affairs of Belarus. At the same time, the countries are ready to respond jointly to emerging external threats," he added, noting that "in the event of external aggression from Poland, Lithuania or other countries, Belarus and Russia will be forced to react".
The protests are the biggest faced by Mr Lukashenko since he took power in 1994, and include members of groups that until now have been his staunchest supporters, including factory and mine workers, state media staff and leading Belarusian sportspeople.
It is not clear, however, whether opposition-led strike action could be widespread enough to put major pressure on his regime.