Thousands of people have been detained as police try to stop nationwide protests in Russia in support of jailed opposition politician Mr Alexei Navalny.
Police are also breaking up groups of his supporters gathered in the capital, Moscow, ahead of a protest there.
Thousands of people have already taken part in rallies in other parts of Russia’s where there were also arrests.
Mr Navalny, President Vladimir Putin’s most high-profile critic, called for protests after his arrest last weekend.
He was detained last Sunday after he flew back to Moscow from Berlin, where he had been recovering from a near-fatal nerve agent attack in Russia last August.
On his return, he was immediately taken into custody and found guilty of violating parole conditions. He says it is a trumped-up case designed to silence him, and called on his supporters to protest.
Prior to the protests, Russian authorities had promised a tough crackdown, with police saying any unauthorized demonstrations and provocations will be immediately suppressed.