Several thousand protesters have marched through central Moscow to call for the release of 20 people who were arrested after clashes between police and demonstrators in May 2012.
Some of them face up to 10 years in prison if convicted for the protest, held on Bolotnaya Square on the eve of President Vladimir Putin's inauguration to a third term as Russia's president.
The protesters marched Sunday with a banner stretching across the street reading: "Freedom to the Bolotnaya heroes, the hostages of Putin." Others held portraits of the jailed protesters.
Of the 28 people who were rounded up in the case, eight were recently freed on amnesty. Several defendants are under house arrest, but most of the others have been in jail for more than a year and a half.