The Investigative Committee called on the State Duma on Monday to repeal the immunity of a Communist Party deputy accused of fighting with police during an unauthorized protest.
Investigators say the dustup occurred at a December rally on the eve of elections in Rostov-on-Don when Vladimir Bessonov, a deputy from the region, refused to follow police orders to switch off a microphone.
Investigative Committee spokesman Vladimir Markin said Bessonov, 56, then attacked officers, damaging their uniforms.
Bessonov, who sits on the Duma's Defense Committee, denies attacking the officers, but described the situation as a "scuffle" in an interview with Izvestia Monday.
He added that police were trying to break the sound equipment that belonged to the protest's organizers while trying to disperse the crowd.
Video clips from the event posted on the websites of local news agencies show several unarmed police officers trying to switch off the microphones that protest organizers were using.
Some of the protesters tried to block their way and one snatched a hat from the head of a police officer. An organizer then shouted "Usurpers!" but there was no sign of serious physical clashes.
Local police said at that time that 15 people had been detained in connection with the event.
Duma Regulations Committee head Ildar Gabdrakhmanov said Monday that his office has not received a formal request from the Investigative Committee regarding Bessonov.
Under the law, the Duma has a week to respond to such a request. The Duma rarely lifts immunity from a deputy. The last time it did so was in October 2010 in the case of banker-turned-deputy Ashot Yegiazaryan, who was accused of fraud in relation to his construction projects.