Police detained Russian opposition leader Boris Nemtsov, a former deputy prime minister, among at least 15 protesters who took part in an unauthorized March of Dissent rally in downtown Moscow on Saturday.

Police also grabbed Sergei Udaltsov, leader of the Leftist Front opposition group.

Prior to that several young people chanting "Shame!" tried to march down Triumfalnaya Square. Police ordered them to stop but then detained them, put them in a bus and took them to a local police station.

Russia's opposition groups came out on the March of Dissent rally in defiance of a city government ban.

In mid-July, city officials authorized a bike festival on Triumfalnaya Square from July 30 through August 1 in what many saw as a deliberate move to snub the opposition's plans.

Moscow city authorities have regularly turned down requests from Russian opposition groups to stage March of Dissent rallies.

Nearly 200 opposition protesters were detained during a March of Dissent rally on May 31.

The crackdown caused public outrage as riot police outnumbered demonstrators and people with disabilities as well as a World War II veteran were reportedly among those detained.

Several small Russian opposition groups hold Marches of Dissent on the last day of each month with 31 days in defense of their right to free assembly, as enshrined in Article 31 of the Russian Constitution.

MOSCOW, July 31 (RIA Novosti)