PRAGUE (Reuters) - Czech police have detained Oleg Vorotnikov, a founding member of the Russian underground art collective Voina, wanted in Russia over a series of high-profile stunts that authorities branded insulting and violent, two media outlets reported.

Voina (War) started in 2007 with stunts poking fun at President Vladimir Putin. It drew greater attention in 2010 by painting a huge phallus on a drawbridge near offices of Russia's FSB security service in St Petersburg.

In November that year, police detained some Voina members, including Vorotnikov, after police cars were overturned in a demonstration to protest against abuse of power by the force. Vorotnikov fled the country in 2011.

Czech daily Hospodarske Noviny said police held Vorotnikov in Prague on Sunday after a routine document check. Police did not confirm the detention but said a 38-year-old foreigner subject to an international warrant had been detained in Prague.

Radio Free Europe also reported Monday evening on its website his wife Natalya Sokol was detained but later released.

The Czech paper cited Sokol as saying they either faced being returned to Switzerland, where they have applied for political asylum, or being deported to Russia.

The Czech justice and interior ministries declined to comment, while Reuters was unable to immediately contact Sokol.

Interpol's Russia office also declined to comment while Russia's interior ministry said it had not received any documents on the detention of Voina members.

Hospodarske Noviny said Vorotnikov was visiting Prague from Switzerland and did not have a Czech visa.

The couple face charges of hooliganism in Russia, which could mean steep jail sentences, media reported.

The group has long been under pressure in Russia for its activities although it has also won the support of activists, like international graffiti artist Banksy.

Voina also has links to punk protest group Pussy Riot, whose member Nadya Tolokonnikova started in Voina. She took part in early "actions", including an orgy staged at a biology museum in support of "the bear cub-successor" - a play on Medvedev's family name and on his close power relationship with Putin.

(Reporting by Petra Vodstrcilova, additional reporting by Moscow bureau; Writing by Jason Hovet; editing by Ralph Boulton)