"According to updated information, the number of detainees has approached 200," Chemodanova said.
A list of detained individuals posted on the website of the Viasna human rights centre shows that detentions have taken place in many cities in Belarus, including Minsk, Grodno, Mogilev, Vitebsk and others.
Weekend opposition rallies have become commonplace across the nation following the disputed August 9 presidential election, in which longtime President Alexander Lukashenko claimed a sixth term.
This past Wednesday, Lukashenko held a clandestine inauguration ceremony, which then reignited the protests.