More than 1,100 people were arrested on Sunday in Belarus during protests calling for President Alexander Lukashenko to resign, a human rights group has said.
The Viasna human rights organisation counted 1,127 arrests, the vast majority of which were carried out in the capital Minsk.
Belarusian authorities said on Monday that more than 700 people had been held in detention following the demonstrations.
"In total, more than 700 people have been detained for violations of the legislation on mass events and before their offenses were examined in court," Interior Ministry spokeswoman Olga Chemodanova said in a statement.
Police in Minsk wielded clubs and used tear gas and stun grenades to disperse thousands of demonstrators. Viasna said that some of the people detained were beaten by the authorities.
Many of the demonstrators on Sunday carried placards in memory of Raman Bondarenko, an opposition supporter who died on Thursday after reportedly being beaten in police detention.
Monday marked one hundred days since President Lukashenko's disputed re-election.
Mass protests have been held weekly across the eastern European country since the August 9 presidential election in which incumbent Lukashenko was credited with more than 80 percent of the vote.
The opposition, the European Union and the United States do not recognise the results.
Lukashenko, who has been in power for 26 years, said on Friday he had asked investigators to probe the Bondarenko's death "honestly and objectively".
Meanwhile, opposition figurehead Svetlana Tikhanovskaya said she met with EU ambassadors and called for further economic sanctions against Belarusian state-owned enterprises and state-linked banks.
Tikhanovskaya, who remains exiled in neighbouring Lithuania, described the former soldier as a "man who was killed because he wanted to live in a free country".
On Sunday she described the crackdown on protesters with "gas, grenades, and firearms" as "devastating" and called for international support for the demonstrators.
"We ask our allies to stand up for the Belarusian people and human rights. We need a humanitarian corridor for the injured, support for the media, international investigation of crimes," she wrote on Twitter.
The EU has already sanctioned Alexander Lukashenko, his son Viktor and several other senior Belarusian officials.
"The whole international reaction is happening thanks to reports of journalists, social media bloggers who constantly post updates," said Hanna Liubakova a non-resident fellow at the Atlantic Council.
"It's important to document wrongdoing and police crimes and atrocities ... so that international investigations can be started".
Supported by Moscow, Alexander Lukashenko refuses to step down from power and has only mentioned vague constitutional reforms to try to calm the protest.