Russian opposition leader Alexei Navalny was released from police custody late on Sunday after a brief appearance at a rally in Moscow calling for the boycott of a March presidential election that he said would be a rigged.
Mr Navalny's lawyer, Olga Mikhailova, told Reuters her client had been released without charge but would have to face court at a later date.
If charged with violating laws on holding demonstrations, Mr Navalny could face up to 30 days in jail.
He had detained soon after joining the Moscow rally, the anti-corruption activist wrote on Twitter. Hundreds of his supporters had joined a nationwide day of protest against the authorities.
Earlier, Russian police had raided Mr Navalny’s Moscow headquarters.
Police forced their way into Mr Navalny’s office using power tools, citing reports of a bomb threat, an online feed run by Mr Navalny’s supporters showed.
Mr Navalny has been barred from running in the March 18th election which polls show incumbent president Vladimir Putin is on track to easily win.
Though MrNavalny says he knows Mr Putin will be re-elected, his spoiler campaign is aimed at lowering voter turnout to try to take the shine off a win by Mr Putin.
Six of MrNavalny's allies were detained during the police raid, OVD-Info, an independent monitoring group, said. It said they were among more than 60 people detained across Russia on Sunday.
Online news bulletins
Police shut down a TV studio at Mr Navalny’s office during the same raid which had been broadcasting online news bulletins, but another studio in a different location continued to operate.
In the Urals city of Yekaterinburg, just under 1,448km east of Moscow, around 1,000 protesters gathered in temperatures of nearly -10 degrees to back Navalny's boycott call.
“No election? No to elections,” a placard being held by one young man read. Other protesters waved Russian flags or red and white placards calling for a boycott.
“We don’t yet have the right to vote,” said Masha (16), who declined to give her surname.
“But we need to think about the future and we want to live in a country where there will be honest elections.”
Yevgeny Roizman, the city’s opposition-minded mayor, said he backed a boycott. “When you see injustice and lies and you can’t change the situation you can at least not take part in it.”
Mr Navalny’s supporters said they expected thousands of people to take part in similar demonstrations in 118 towns and cities.
“Your own life is at stake,” Mr Navalny said in a pre-protest video. “How many more years to do you want to live with these thieves, bigots and creeps?”
Police warned beforehand they would harshly suppress any illegal protest activity and authorities refused to authorise events in Moscow and St Petersburg, the country’s two biggest cities, raising the possibility of clashes.
Heavy police presence
A reporter saw a heavy police presence in central Moscow ahead of the protest, with a command centre and buses filled with policemen parked on side streets.
Mr Navalny, a lawyer who has campaigned against official corruption, was barred from running for the presidency by the central election commission in December over what he said was a trumped-up suspended prison sentence.
The United States and the EU criticised the decision.
Mr Putin, who has dominated the Russian political landscape for nearly two decades, described US criticism of the election commission’s decision as crude interference in Russia’s internal affairs and suggested Mr Navalny was Washington’s pick for the presidency.
Polls show Mr Navalny had scant chance of beating Putin, but Mr Navalny says the system is rigged against political opponents like himself which makes polls meaningless. - Reuters