Moscow, Dec 7 (IANS/RIA Novosti): A prison in Russia's Urals region where inmates rioted last month against alleged abuse and extortion has been compared to a "concentration camp" by a member of the Kremlin's human rights council.

"We saw a splendid park and a beautiful church, marble - but behind the facade there was hell," Maxim Shevchenko said at a news conference.

"One of the inmates had been spread out on bars, a helmet with speakers was put on his head, and a siren turned on," he said after a visit by council members to the prison.

Around 500 inmates at Prison No.6 in Kopeisk, in Chelyabinsk region, rioted Nov 25-26 over alleged widespread abuse by prison guards. Eight police officers were injured in the disturbances, during which inmates climbed onto the prison roof and held up a make-shift banner reading "People, help us".

Riot officers were also reported to have clashed with hundreds of relatives of inmates who had gathered outside the prison.

Kremlin human rights council chief Mikhail Fedotov said Thursday a number of inmates had been held in isolation cells for "months or even years".

"There was one man who could only crawl. His legs didn't work anymore after being kept in a punishment isolation cell for months."

The disturbances made headlines across Russia and were the subject of intense online debate by the country's increasingly politicized internet community.

Police also made 12 arrests at a Nov 26 protest against torture in the Russian prison system outside the Moscow headquarters of the Federal Penitentiary Service.

Investigators have since filed assault charges against five inmates. One prison guard has also been charged with extortion.

"People who complained (about extortion) were beaten," council member Igor Kalyapin said, adding that "a stream" of complaints to local officials about the alleged abuse had been ignored.

Chelyabinsk Governor Mikhail Yurevich said the riot was sparked by a "corrupt" system.

More than 700,000 Russians are currently behind bars. Human rights activists frequently complain of sub-standard living conditions, torture, and disease in the country's prisons.