A dubious prison sentence for a young actor arrested during demonstrations in Moscow has sparked a backlash from famous cultural figures who normally stay out of politics, raising pressure on the authorities over their crackdown on protesters.

Hundreds of people including well-known actors waited hours outside the presidential administration on Wednesday to take their turn in a single-person picket in support of Pavel Ustinov, 24, who was given a three and a half year prison sentence on Monday for allegedly dislocating a riot policeman's shoulder during chaotic street protests in August.

Single-person pickets are the only form of protest that doesn't typically result in arrests.

The court refused to consider videos showing that Mr Ustinov, who has played small roles in films, was calmly waiting outside a metro station when a group of riot police officers ran up and tackled him to the ground, beating him with batons.

“Our legal system is horrifying. There need to be reforms and investigations into why judges make these convictions and why security agencies act in this way,” Alexander Pal, an award-winning actor who called the pickets, told the Telegraph.