Police have detained several activists who were trying to hold a rally on Moscow's Bolotnaya Square on the second anniversary of unrest that broke out there.
The Russian rights website ovdinfo.org reported 12 activists and one journalist were taken into custody on May 6 after they unfurled banners on Bolotnaya Square.
Moscow city authorities had warned in advance they would not permit any rallies on the square to mark the two-year anniversary.
On May 6, 2012, Russian opposition groups staged the "March of Millions" that ended in clashes between demonstrators and police on and around Bolotnaya Square.
The violence took place on the eve of Vladimir Putin's inauguration for a third term as president.
More than 400 people were detained, 28 were put charged for their parts in the unrest.