Hundreds of people were detained as anti-corruption rallies across Russia descended into violence.
Riot police arrested activists at protests in cities including Moscow and St Petersburg on Monday.
Opposition leader Alexei Navalny was detained at his home before the rallies began, according to his wife.
He wife Yulia confirmed in a tweet posted on his account that the Putin critic was arrested on his doorstep just before demonstrations he had called for began.
The BBC reported that police were picking protesters out of the crowds at random and video footage showed officers pushing activists to the ground and dragging them by their necks.
Police were also seen using metal fences to drive back the protesters, who reportedly chanted slogans such as "Russia without Putin" and "Putin is a thief".
The post by Mr Navalny's wife said: "Alexei has been arrested in the entrance to our block of flats."
According to NGO OVD-Info, which monitored the protests, 600 people were detained at the Moscow protests and 300 at the rally in St Petersburg.
A veteran anti-corruption activist, Mr Navalny - who had hoped for the protests to be non-violent - has experienced numerous encounters with the law after he continued to publish blogs critical of the Russian president.
Described by the Wall Street Journal as "the man Vladimir Putin fears most", Mr Navalny has been arrested numerous times and twice prosecuted on embezzlement charges, which he denied.
In April this year, Mr Navalny was set upon outside the offices of his Anticorruption Foundation by an attacker who sprayed his face with a green antiseptic called zelyonka.
According to comments published in Radio Free Europe/Radio Liberty, he claims to have lost 80 per cent of sight in his right eye as a result of the attack.
