Police detained 14 people including opposition politician Ilya Yashin at a sit-in protest against President Vladimir Putin Wednesday in Moscow's popular Gorky Park.
Police swiftly detained protestors including Yashin, who regularly speaks at protest rallies, after they attempted to hold a sit-in protest at the park.
"They put me into a police van for clapping," Yashin wrote on Twitter, saying 12 detainees were taken to a police station.
Two other protestors were detained separately, Left Front radical group wrote on Twitter.
The protest involving around 50 activists came after thousands turned out for a sanctioned rally condemning Putin in central Moscow on Monday.
The protest, called "Occupy Gorky", was announced on Facebook.
The organisers said the protest "signals the beginning of an unlimited struggle for city spaces, for freedom of speech, for political rights -- for everything the Putin system is methodically taking away from us."
Gorky Park this month opened a site where the public are allowed to give political speeches, loosely based on Speakers' Corner in Hyde Park in London.
It has been criticised by the opposition as a token gesture to justify refusing rally requests.