KYIV, Ukraine – Club-swinging police went after demonstrators in Belarus’ capital who were demanding the resignation of the country’s authoritarian president on Sunday, the 90th consecutive day of protests.

Human rights activists said hundreds of people were arrested.

Thousands of demonstrators tried to enter the centre of Minsk from several directions, but police cordoned off the area with armoured vehicles and phalanxes of riot officers and prevented the protesters from assembling in a single place.

The Belarusian Association of Journalists said at least nine journalists were detained. The human rights organization Viasna said 548 people were arrested in all, including well-known model Olga Khizhinkova, a former Miss Belarus.

The wave of protests, unprecedented in their size and duration, began after the Aug. 9 election that official results say gave President Alexander Lukashenko a sixth term in office. The opposition and some poll workers say the results were manipulated.

Lukashenko, who has suppressed opposition and independent news media since coming to power in 1994, has refused dialogue with opponents and has alleged that Western countries have incited the protests.

His main election challenger, Sviatlana Tsikhanouskaya, who fled to Lithuania under pressure from officials after the election, on Sunday expressed hope that Joe Biden, the U.S. president-elect, would put pressure on Lukashenko.

“Joe Biden has spoken out more than once and taken a firm position of support for the Belarusian people,” she said.

She also exhorted protesters to continue demonstrating.

“We have stood against lawlessness and violence for 90 days already. In these 90 days, Belarusians made the regime understand that they have lost legitimacy and authority,” she said.