KYIV, Ukraine (AP) — Police in Belarus on Sunday arrested more than 160 participants in demonstrations calling for the ex-Soviet nation’s authoritarian president to resign.

Protests have rocked the ex-Soviet nation for the sixth straight month following the Aug. 9 presidential vote, which was widely seen as rigged to give President Alexander Lukashenko a sixth term in office.

The protests, which attracted 100,000 people or more at their peak, were the most serious challenge to Lukashenko, who has relentlessly suppressed the opposition during 26 years in office. According to human rights advocates, more than 30,000 people have been detained since the protests began, and thousands of them were brutally beaten.

The fierce crackdown drew international outrage, and the United States and the European Union have imposed sanctions on Belarusian officials.

During Sunday’s protests in Minsk and several other cities in Belarus, hundreds of people waving the opposition red-and-white flags gathered in their courtyards and marched in their neighborhoods. Police arrived quickly, chasing protesters and detaining scores.

“We witness a tough reaction from the authorities, but large numbers of people continue to turn out to protest despite the repressions and frigid cold,” Viasna human rights group leader Ales Bialitski said in a telephone interview.