KYIV, Ukraine -- Belarusian authorities on Monday enforced tight security measures to prevent an opposition rally marking the anniversary of the Chernobyl nuclear catastrophe.
The military and police flooded the center of the Belarusian capital, Minsk, blocking central avenues to thwart a planned march. Police arrested about 20 people, according to the Viasna human rights group.
Earlier in the day, several dozen women dressed in black and wearing black masks staged a demonstration on the outskirts of the capital.
The tough police action is part of the authorities' relentless crackdown on protests were triggered by Belarusian President Alexander Lukashenko's re-election to a sixth term in an August election that the opposition saw as rigged.
The massive demonstrations sparked by the vote attracted as many as 200,000 people. More than 34,000 were arrested during months of protests, and many of them were beaten by police. Most prominent opposition figures have fled Belarus or have since been jailed.
In the past years, the opposition marked the anniversary of the Chernobyl nuclear catastrophes with annual marches, reflecting the massive damage the country has suffered.
Reactor No. 4 at the Chernobyl power plant in then-Soviet Ukraine exploded and caught fire on April 26, 1986, spewing radiation across Europe in the world's worst nuclear accident.
President Lukashenko took part in a requiem rally for the Chernobyl disaster Monday in the town of Bragin, some 360 km (225 miles) south-east of Minsk.
The Belarusian opposition has charged that the authorities have been concealing the true scope of the catastrophe, which has contaminated larges swathes of land in Belarus.
Sviatlana Tsikhanouskaya, the main opposition challenger in the August vote who left Belarus under official pressure, denounced the post-election crackdown as a “political and humanitarian Chernobyl.”