Eight Russian policemen were injured trying to disperse a crowd outside a prison where 250 inmates staged a roof-top protest demanding the release of a group of fellow prisoners from a punishment cell, authorities said on Sunday.
Russian state television showed pictures of a group of inmates standing on the roof of the prison holding white banners reading "people, help" in the town of Kopeysk near the industrial city of Chelyabinsk in the Urals mountains.
Details of the incident remain unclear with human rights activist Oksana Trufanova telling the Echo Moskvy station that OMON special police troops attacked a group of inmates' relatives outside the prison.
"They beat us with batons. Their eyes were shining. I had never been in such mayhem," Trufanova said. Police said 38 people were detained, but denied OMON officers had beaten people outside the prison.
Trufanova said the protest was a consequence of regular beatings in Kopeysk prison. The local prison authority said in a statement the situation inside the prison was now stable and under control.
Police said the troops were attacked by groups of drunken youths who were throwing bottles and shouting obscenities. Prison mutinies in Russia are relatively rare.
More than 700,000 Russians are currently behind bars and human rights activists regularly complain of poor living conditions, cases of torture, beatings and disease in prisons.
Conditions in Russian prisons came to international attention after Sergei Magnitsky, a lawyer for equity fund Hermitage Capital died a Moscow prison. The Kremlin's own human rights council says he was probably beaten to death.
The local prison authority said the protesters had no demands other than the release of a group of their fellow inmates from a punishment cell. It said the group had violated prison rules and the demand to release them was illegal.