Opposition supporters in Belarus are holding a mass rally in the capital Minsk, two weeks after a disputed election gave President Alexander Lukashenko another term in office.
People have been flowing in the central square, despite heavy police presence.
The protesters say Mr Lukashenko stole the election and want him to resign.
The president has vowed to crush the unrest and has previously blamed the dissent on unnamed “foreign-backed revolutionaries”.
Recent protests have been met with a crackdown in which at least four people have died. Demonstrators said they had been tortured in prisons.
According to official results, Mr Lukashenko – who has ruled Belarus for 26 years – won more than 80% of the vote in the 9 August election and opposition leader Svetlana Tikhanovskaya 10%.
There were no independent observers, and the opposition says there was massive vote rigging.
Ms Tikhanovskaya, who was forced to flee to neighbouring Lithuania the day after the election, vowed to “stand till the end” in the protests.
What is happening in Minsk?
Tens of thousands of people – from the elderly to those with small children – gathered in Independence Square on Sunday. Many were carrying red and white flags or white flowers, and chanted “freedom” and anti-government slogans.
Riot police took up positions near the square, with loudspeakers blaring warnings that the protest was illegal.
The defence ministry issued a statement invoking Belarus’s sacrifices during World War Two, and saying the army would take over the protection of war memorials.
This weekend’s rally follows the country’s biggest protest in modern history last Sunday, when hundreds of thousands filled the streets.
Strike action in key factories across the country is also keeping up the pressure on the president.
What has Lukashenko said?
The 65-year-old president insists he won the election fairly and has ruled holding another poll. On Saturday he accused Nato of “trying to topple the authorities” and install a new president in Minsk.
He said he was moving troops to the country’s western borders to counter a Nato build-up in Poland and Lithuania, and vowed to “defend the territorial integrity of our country”.
Nato responded by saying it posed “no threat to Belarus or any other country”, and had “no military build-up in the region”.
“The regime is trying to divert attention from Belarus’s internal problems at any cost with totally baseless statements about imaginary external threats,” Lithuanian President Gitanas Nauseda told AFP news agency on Saturday.
Mr Lukashenko has also accused an opposition council – set up by Ms Tikhanovskaya to organise peaceful transition – of trying to seize power. Two of its members were questioned by police on Friday.
Belarus – the basic facts
Where is Belarus? It has Russia – the former dominant power – to the east and Ukraine to the south. To the north and west lie EU and Nato members Latvia, Lithuania and Poland.
Why does it matter? Like Ukraine, this nation of 9.5 million is caught in rivalry between the West and Russia. President Lukashenko, an ally of Russia, has been referred to as “Europe’s last dictator”. He has been in power for 26 years, keeping much of the economy in state hands, and using censorship and police crackdowns against opponents.
What’s going on there? Now there is a huge opposition movement, demanding new, democratic leadership and economic reform. Mr Lukashenko’s supporters say his toughness has kept the country stable.