Hundreds of Russian opposition supporters turned out Saturday to protest against President Vladimir Putin's expected candidacy in elections set for 2018, with police detaining dozens of activists in the second-largest city of Saint Petersburg.
Protests in several cities were called by the Open Russia movement founded by arch-Putin foe and former oil magnate Mikhail Khodorkovsky.
They were held under the slogan "We're sick of him" -- referring to Putin.
About 30 to 50 protesters were hauled away by riot police in a crackdown in Saint Petersburg after around 200 people gathered for an unauthorised demonstration, an AFP journalist witnessed.
Open Russia put the figure of detentions at about 50 people, while OVD-Info, which monitors detentions of political activists, said more than 125 were detained. Police have not yet issued numbers.
"Putin is an usurper. He has to finally go. We're sick of him," said one of the protesters, 35-year-old Anton Danilov.
"Everything is bad. Education, health -- everything has been destroyed. I want changes," said Galina Abramova, 57.
A similarly sized protest in Moscow remained peaceful as activists gathered at the offices of Putin's administration and handed in petitions against his expected candidacy in 2018.
"I don't want Putin to stand in the next elections," said Anna Bazarova, a 16-year-old student queuing up to hand in her petition.
"Our main problem is that we can't change those in power," she said.
She added that many of her friends had opted not to attend, fearing detention by the police.
Riot police stood guard as officers used loudspeakers to warn protesters: "Citizens, your action has not been agreed by the authorities."
One of the organisers, Yakov Yermakov, handed out forms for people to fill out with complaints to Putin.
"Our president has already been in power 17 years. We think that's too long. Our country isn't developing," he said.
The protests came after opposition leader Alexei Navalny organised the largest unauthorised rally of recent years in Moscow on March 26. Police detained around 1,000 people, including Navalny.
Navalny has announced his plan to stand for president in 2018 and has galvanised the splintered opposition movement with a powerful online campaign including videos exposing corrupt officials. He has called for another protest on June 12.
The main figurehead of Saturday's protests, Khodorkovsky, remains a highly controversial figure in Russia. The former oligarch and founder of the Yukos oil company spent a decade in prison and now lives in Britain.
His Open Russia movement has been targeted by the authorities recently with police raiding its Moscow offices this week.