Update 12.10pm: Russian opposition leader Alexei Navalny has been arrested in Moscow as protest demonstrations called by him took place across the country.
He has called on supporters to continue the demonstrations despite his arrest Sunday.
He said on Twitter: "They have detained me. This doesn't mean anything ... you didn't come out for me, but for your future."
Меня задержали. Это значения не имеет. Приходите на Тверскую. Вы не за меня выходите, а за себя и своё будущее.— Alexey Navalny (@navalny) January 28, 2018
Protests ranging from a few dozen to several hundred people were reported throughout the country.
Mr Navalny is calling for a boycott of the March 18 presidential election in which President Vladimir Putin is seeking a fourth term.
Earlier 11.48am: Police raid Russian opposition leader's HQ as protests arise
Russia police have raided the Moscow office of opposition leader Alexei Navalny as demonstrations calling for a boycott of Russia’s presidential election take place across the country.
A video stream on Sunday morning from Mr Navalny’s headquarters showed police entering the office.
One broadcaster on the stream said police apparently were using a grinder to try to get access to the broadcast studio.
The anchors said police say they had come because of a bomb threat.
Mr Navalny, who has been blocked from running in Russia’s March 18 presidential election, called for nationwide protests on Sunday.
Sizeable gatherings have been reported in the Far East and Siberia, including Vladivostok, and more are set for Moscow and St Petersburg in the afternoon.