Russian opposition leader Alexei Navalny has been detained by police in Moscow after joining a rally in support of a presidential election boycott.
“I have been detained,” Mr Navalny, 41, tweeted (in Russian).”This means nothing,” he added, urging his backers to join protests across Russia.
Earlier, police raided his offices in Moscow, reportedly seizing equipment.
Mr Navalny – President Vladimir Putin’s most vocal critic – is barred from standing in the 18 March election.
Footage posted on Mr Navalny’s Twitter page showed him being wrestled to the ground by policemen during the arrest.
The opposition leader later tweeted: “The detention of one person is meaningless if there are many of us. Someone, come and replace me.”
Protest rallies are being held in a number of Russian cities. In Moscow and St Petersburg they were not sanctioned by authorities.
More than 180 people have so far been detained across the country, reports say.
Earlier on Sunday, Russian police raided the property of Mr Navalny’s anti-corruption organisation in Moscow.
A spokesman for Mr Navalny said the officers used a power tool to break into the office, adding that they said they were investigating a bomb threat.
The demonstrations come after weeks of pressure on Mr Navalny’s supporters across Russia, who have faced detentions and had leaflets in support of the rallies confiscated.
Mr Navalny, who insists he would beat Mr Putin in a fair fight, is barred from running in the ballot over a criminal conviction that he says is politically motivated.
The opposition leader led mass street protests against Mr Putin in the winter of 2011-12 and was arrested three times in 2017 for organising unauthorised anti-Putin protests.
Mr Putin, who refuses to mention Mr Navalny by name, retains a massive approval rating in Russia and is widely expected to win a fourth six-year term in office.