Belarusian authorities have detained hundreds of people during an attempt to hold a street protest in the capital, Minsk, amid rising public anger over falling living standards and an unpopular tax on the unemployed.
Protesters shouting slogans and waving signs were taken away, many of them beaten, along with passersby and at least ten journalists.
A Reuters reporter saw hundreds of police deployed to block off access points to the square where the protests were due to take place.
Nearby metro stations were closed and three water cannons kept on standby.
Police earlier also raided the offices of Vesna-96, an opposition group, and detained about 60 activists, although they were later released, Vesna-96 said.
The demonstration is the latest in a wave of protests since February that pose the biggest challenge in years to President Alexander Lukashenko, who has ruled the ex-Soviet state with an iron fist for nearly a quarter of a century.
Belarus has been in recession for the past two years, suffering the knock-on effects of an economic downturn in Russia and a sharp fall in oil prices.
The hardship has brought even former Lukashenko supporters onto the streets.
The trigger for the unrest was a tax on citizens working less than 183 days a year, locally known as a law against "social parasites".
Belarusians said the tax unfairly punished those unable to find work.
Mr Lukashenko has suspended the tax in light of the backlash but the protests have continued.
Today's crackdown was the culmination of the authorities hardening their position on the protests.
Earlier this week Mr Lukashenko accused a "fifth column" of plotting to overthrow him with the help of foreign-backed fighters.
On Friday he built on this theme, saying "someone wants to blow up the situation, and they use our scumbags".
It is unclear as yet how the crackdown on the protests will affect relations with Belarus's neighbours.
Mr Lukashenko has sought to improve ties with the West against the backdrop of cooling relations with ex-Soviet master Russia.
He has pardoned several political prisoners, spurring the European Union to lift sanctions against a country once described by the United States as "Europe's last dictatorship".