As many as 200,000 protesters marched in the Belarusian capital of Minsk – far outnumbering the crowd of longtime authoritarian leader Alexander Lukashenko supporters who also marched.
Various chants were heard from the anti-government demonstrators, including “Long Live Belarus” and demands that Lukashenko "Go away."
"We aren't in the stone age. Belarus is in the 21st century, and no matter where our ex-leader takes us, we won't use arms against the authorities," Protester, Anton Svobodsky, said.
One banner read “Hague, take him,” a reference to the headquarters of the International Criminal Court.
The march began near Victory Park in central Minsk and was the biggest protest in the history of the former Soviet republic.
The marchers were supported by about 1,000 demonstrators in Prague.
Czech Prime Minister Andrej Babis recalled how Czech protests were crushed by a Moscow-led military invasion in 1968 – the Prague Spring. But he also remembered the peaceful overthrow of communism in 1989 and called on the European Union to help in Belarus.
About 50,000 Lukashenko supporters also gathered in Minsk to hear the president say he will not hold another vote after the election commission declared him the winner last week with 80% of the vote.
“NATO troops are at our gates. Lithuania, Latvia, Poland and our native Ukraine are ordering us to hold new elections,” Lukashenko. “I have never betrayed you and will never do so.”
One Lukashenko supporter said, “Everybody suddenly has forgotten the good things he has done — there’s order in the country, we don’t have war or hunger.”
The West calls him “Europe’s last dictator” for his suppression of free speech and human rights and little tolerance for the opposition.
He has long been accused of cozying up to Moscow at the expense of better ties with the West.
The country's Central Election Commission said the Monday after the election that after all ballots were counted, Alexander Lukashenko took 80.23% of the votes and the main opposition candidate Sviatlana Tsikhanouskaya 9.9%.
She entered the race after the arrest of her husband, blogger and a would-be opposition candidate Siarhei Tsikhanousky was arrested.
Tsikhanouskaya said she would never accept the results before fleeing to Lithuania for what she said was her children’s safety.
Lukashenko took power after Belarus declared independence from the Soviet Union and has been president since 1994.
Lukashenko told military chiefs Sunday that Russian President Vladimir Putin offered "comprehensive help" to "ensure the security of Belarus."
A Kremlin said in a statement that both presidents agreed the "problems" in Belarus would be "resolved soon" and the countries' ties would strengthen.