MOSCOW — Hundreds of Russian prisoners have slashed their wrists, necks, and legs in a gruesome protest over prison conditions and alleged abuse by penal authorities.

The regional prosecutor’s office in Lgov, about 310 miles south of Moscow, said yesterday that 260 prisoners had used razor blades to inflict the wounds on themselves Monday night. The office said in a statement that they suffered only light injuries and were being cared for by a team of doctors.

But human-rights workers who had been in contact with the prisoners by telephone said that as many 700 inmates had been involved in the protest.

A spokesman for Russia’s Movement for Human Rights, Yuri Davidenko, said the inmates were protesting against Russia’s notoriously bleak prison conditions and frequent abuse. He said that the families of more than 50 of the inmates were also demonstrating in front of the facility.

“They’re protesting against the gross violations of human rights that are common in Russian prisons,” Mr. Davidenko said. “This act was provoked by psychological abuse and physical attacks [the inmates] suffer. … They did this because they felt they had no other choice, that there was no other way to make people listen.”

The prosecutor’s office said it had opened a criminal investigation against the prison administration for abuse of authority.

The office said that “the self-mutilation had obviously been planned in advance because the action began simultaneously in 10 sections of the prison.” It said that when doctors arrived to examine the protesters they discovered evidence of possible beatings and torture.

“Cases of unreasonable application of physical force by employees were revealed in regards to numerous inmates,” its statement said.

The regional prosecutor, Alexander Babichev, said that inmates were demanding improved conditions and the firing of the prison’s current administration. He said an initial investigation backed up allegations of abuse.

“Facts concerning the illegal treatment of detainees have been established and those who allowed these violations will be prosecuted,” he said on national television.

The Russian prison service, however, condemned the protest as an act of disobedience.

“The inmates’ actions were aimed at destabilizing the situation in the jail and were motivated by their refusal to accept legitimate demands of prison authorities for the enforcement of detention rules,” it said in a statement.

Russia’s 767,000-strong prison population is the third-largest in the world after America and China. International human rights groups and foreign governments have criticized Russia’s prison system as antiquated and rife with abuse. Overcrowding has led to massive outbreaks of disease, with about 75,000 Russian prisoners infected with tuberculosis and 36,000 infected with HIV. In its 2004 Human Rights Report on Russia, the State Department said “prison conditions remained extremely harsh and frequently lifethreatening,” citing habitual abuse, poor sanitary conditions, and lack of medical care.

Russian inmates have previously used self-mutilation to protest against prison conditions, but this week’s incident appears to be the largest in recent years.In April,10 prisoners on a hunger strike in the eastern city of Irkutsk were prevented by guards from slashing their wrists in protest.In 2003,nearly 50 teenage inmates in a penal colony in Kazan used glass shards and razor blades to cut their hands and faces in protest over conditions.

This week’s protest also follows a similar incident earlier this month in Australia, when 13 Chinese refugee claimants slashed their wrists at a camp near Sydney to protest the country’s asylum rules. None of the Chinese protesters were seriously injured.