Russia faces to watch: Alexei Navalny
The BBC looks at some of Russia's key opposition figures.
Alexei Navalny is considered by many in Russia to be the country's most promising opposition leader.
The young lawyer first came to public attention as a blogger who ran a number of anti-corruption campaigns which exposed the excesses of Russia's political elite.
However, he gained wider popularity after getting involved in the mass opposition rallies in 2011, becoming one of their informal leaders.
He was arrested along with 300 protesters on 5 December and spent 15 days in prison.
He is trusted by many nationalists and distrusted by some liberals because of comments he has made against illegal immigration and because he attended the Russia March, a nationalist demonstration with strong far-right connections.
He was expelled by the left-liberal Yabloko party in 2007 over what it said were his "nationalistic activities".
But his commitment to democracy, political pluralism and the free market have given him wide appeal.
He coined the catch-phrase "party of crooks and thieves" which is now widely used by the opposition to describe Vladimir Putin's United Russia.
He has said he would be ready to run for president if elections were free and fair. But he says the voting system needs to be cleaned up first.
Through the internet he has built up a network of supporters in towns throughout Russia - people who share his anger at corrupt officials.
His Moscow apartment was among the homes of opposition activists raided by police on 11 June, 2012. He went on Twitter to complain about the police, who "almost carved up the door". He said they spent hours inside, and removed computer disks containing photos of his children, along with items of clothing.