Russian police say they detained 55 opposition supporters near Moscow's Red Square in order to prevent an unauthorized anti-government rally there.
Activists had called for supporters to walk around the square, located outside of the Kremlin, wearing white ribbons as a symbol of the protest movement.
But police closed the square and blocked off its access roads, preventing the gathering.
Russian opposition activists have criticized the government for violating their right to freedom of assembly.
Tens of thousands of activists have rallied in recent months against widespread fraud in the parliamentary election and against Vladimir Putin's election as president last month.
Some information for this report was provided by AP, AFP and Reuters.