Belarusian police arrested 633 people on Sunday in protests across the country. The Ministry of the Interior said this in a statement.
Russian news agency Interfax reported more than a hundred arrests on Sunday evening.
The human rights group Viasna estimated the number of arrests across the country at about 250, of which 175 in the capital Minsk.
Authorities crackdown on mass demonstrations against Belarusian leader Aleksandr Lukashenko.
These broke out after the presidential election on 9 August, which was fraudulent in the eyes of the opposition and the international community.
Over the previous weekends, it is estimated that more than 100,000 people took to the streets in Minsk. According to journalists from the AFP news agency, the protest may have been even more massive this Sunday, despite the bad weather.
Photos and videos show security forces taking action against peaceful protesters. Men, in particular, were taken away.