Russian police have detained opposition leader Alexei Navalny at a demonstration against President Vladimir Putin in central Moscow.
Thousands of demonstrators denouncing Mr Putin's upcoming inauguration into a fourth term gathered in the capital's Pushkin Square.
Video showed police carrying a struggling Mr Navalny, who is Mr Putin's most prominent foe, out of the square, carrying him by the legs and arms.
The unauthorised protest was part of a day of nationwide demonstrations under the slogan "He is not our tsar."
Police made arrests at demonstrations in some other cities, but there was no overall figure immediately available.
News reports and social media postings said protests had attracted hundreds or more in at least 10 cities in the Far East and Siberia.
Putin will be inaugurated Monday for a six-year term.