A Moscow court on Monday convicted an opposition activist of being a member of the banned National Bolshevik Party, a ruling the radical youth group said could spark a wave of similar convictions.

The Arbat District Magistrates Court convicted Murmansk resident Andrei Nikitin, 20, of participating in a group banned for extremist activities and handed him a one-year suspended sentence with two years probation, Moscow City Court spokeswoman Anna Usachyova said.

The verdict was the first conviction for a National Bolshevik activist on charges of being a member of the opposition group, though dozens of others have been convicted in recent years on charges including hooliganism and assault, said Alexander Averin, a spokesman for the group.

The ruling could set a precedent for convictions of other National Bolsheviks, Averin said.

"This is the first such case, but it may not be the only one," Averin said. "There are a number of other criminal cases where our members are facing similar charges."

Writer and opposition leader Eduard Limonov, who founded the National Bolshevik Party in 1993, has claimed that the group has more than 50,000 members nationwide.

In April 2007, the Moscow City Court declared the unregistered party, known for its theatrical protests, an extremist organization.

The ruling, subsequently upheld by the Supreme Court, allows authorities to prosecute anyone who takes part in the group's activities.

Nikitin was charged in connection with a February stunt in which he hurled National Bolshevik leaflets inside the Khudozhestvenny movie theater near Arbatskaya metro station in central Moscow, a spokeswoman for the magistrates court said.

The spokesman declined to give her name or further details on the case.

Averin said Nikitin was protesting the premiere of a film called "A Kiss -- Not for the Press," based on the life of then-President Vladimir Putin.