Russian police on Saturday detained dozens of opposition activists who had tried to hold a demonstration in central Moscow on Constitution Day.
The liberal opposition Yabloko party had planned to distribute a pamphlet outlining the rights guaranteed under the Russian Constitution and how it believes they are systematically being violated in the country now.
News reports said police detained 33 people, including Yabloko leader Sergei Mitrokhin. He told the Interfax news agency that he and four others had been told by police they would be held until Monday, but when police failed to produce the proper documentation, they walked out of the police station.
Mitrokhin earlier posted a photograph on Twitter of himself and 10 other activists in the police station, with one of them holding a sign reading: "Respect our Constitution.''
The Russian Constitution was adopted in 1993 under Boris Yeltsin, the first president of Russia after the 1991 fall of the Soviet Union.
Since Vladimir Putin was first elected president in 2000, Russia has seen a steady erosion of democratic and civic institutions. The opposition has largely been barred from elections and national television has been put under Kremlin control.