TEHRAN, Iran - After months of denials, Iran acknowledged yesterday that at least three people detained in the country's postelection turmoil were beaten to death by their jailers.

The surprise announcement by the hard-line judiciary confirmed one of the opposition's most devastating and embarrassing claims against authorities and the elite Revolutionary Guard forces that led the crackdown after June's disputed presidential vote.

There was no immediate public reaction from the opposition, but some activists asserted that authorities under pressure over abuse claims were merely seeking to punish low-ranking staff while shielding senior level officials who the opposition says are most to blame.

Still, the statement offered some rare vindication for the government's critics, who had rejected earlier explanations from the police and the judiciary that the detainees' deaths were caused by illnesses such as meningitis, not physical mistreatment.

"The coroner's office has rejected that meningitis was the cause of the deaths and has confirmed the existence of signs of repeated beatings on the bodies and has declared that the wounds inflicted were the cause of the deaths," the judiciary statement said, according to the Web site of Iran's state TV.

The judiciary also said it has charged 12 officials at Kahrizak prison - three of them with murder, but it did not identify them. The prison, on the southern outskirts of the capital, Tehran, was at the center of the opposition's claims that prisoners were tortured and raped in custody.

Anger over the abuse claims, which emerged in August, extended far beyond the reformist camp, with influential conservative figures in the clerical hierarchy condemning the mistreatment of detainees.

The outrage forced Supreme Leader Ayatollah Ali Khamenei to order the immediate closure of the prison.

The opposition says at least 72 protesters were killed in the postelection crackdown, but the government puts the number of confirmed dead at 30.

Authorities initially tried to repel the abuse claims by accusing the opposition of running a campaign of lies against the ruling system. President Mahmoud Ahmadinejad had even accused Iran's enemies of being involved in the crimes, a claim the opposition rejected as ridiculous.

Iran's police chief, Gen. Ismail Ahmadi Moghaddam, said in August that protesters were beaten by their jailers at Kahrizak, but he maintained at the time that the deaths were not caused by the abuse.

The opposition's criticism was implicitly aimed at the country's most powerful military force, the Revolutionary Guard, which operates with some autonomy from the ruling clerics and led the harsh crackdown and detention of protesters in the tense weeks after the election.

The unrest broke out after proreform candidate Mir Hossein Mousavi claimed he was robbed of the presidency through massive vote fraud.

Pressure regarding the abuse claims accelerated in early August.

One of the other pro-reform candidates defeated in the election, Mehdi Karroubi, said then that he had received reports from former military commanders and other senior officials that some detainees, male and female, were raped in custody to the point of physical and mental injury.