Police and judiciary officials sought on Sunday to calm public outrage in Iran over the deaths of detained protesters in prison, acknowledging abuses and calling for those responsible to be punished. A senior commander of the powerful Revolutionary Guard, which led the crackdown against the protesters, meanwhile, said that the three top opposition figures are the ones who should be put on trial, striking a harder line that suggests tensions at the highest levels of Iran's power structure. Iran's Prosecutor General Ghorban Ali Dorri Najafabadi called for those responsible for mistreating detainees to be punished, saying that the protesters weren't even meant to be taken to Kahrizak prison, which has been at the center of abuse claims. "Unfortunately, negligence and carelessness by some officials caused the Kahrizak incident, which is not defendable," he told the state news agency. "During early days, it is possible there were mistakes and mistreatment due to overcrowding in the prison." His comments were followed up by police chief Gen. Ismail Ahmadi Moghaddam who acknowledged protesters were beaten by their jailers at the same facility and its head has since been arrested along with three guards there and the prison closed down. However he maintained that the deaths in the prison were not caused by the abuse. "This detention center was built to house dangerous criminals. Housing people related to recent riots caused an outbreak of disease," the official news agency quoted Moghaddam as saying. Protesters "died of viral illness and not as a result of beating." Anger of the events at Kahrizak has extended far beyond just the reformist camp, with influential figures in the clerical hierarchy condemning the abuse of detainees and the three deaths known to have taken place there. Conservative lawmaker Hamid Reza Katouzian rejected the police chief's explanation that illness was to blame for detainee deaths. "Murders were committed that led to the loss of life of a number of our youth. This has to be probed," the semiofficial ISNA news agency quoted him as saying in an echo of reformist demands that those involved in the abuse be put on trial. Mohsen Rezaei, a conservative who ran against President Mahmoud Ahmadinejad in the elections, has led the demands for high-level probes into abuses. The son of Rezaei's top aide, Abdolhossein Rouhalamini, died in detention. He was arrested during a July 9 protest and taken to a hospital two weeks later where he died within hours. Iran has confirmed at least 30 people have died in the worst internal unrest since the 1979 Islamic Revolution, though human rights groups believe the death toll is probably far higher. Hundreds have been detained. The criticisms are implicitly aimed at the elite 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. A senior guard commander struck back on Sunday and challenged the judiciary for not going after the three top opposition leaders, Mir Hossein Mousavi, Mahdi Karroubi and former president Mohammad Khatami themselves, who initially led the protests over the June 12 elections on the grounds they were rigged. "If Mousavi, Khatami ... and Karroubi are the main elements of a velvet coup in Iran, which they are, it is expected that judicial bodies and intelligence officials go to them to put out the fire of sedition, arrest, try and punish them," Yadollah Javani said, according to IRNA. The Guard was created following the 1979 Islamic revolution as an ideological force to defend Iran's clerical rule. The 120,000-strong force is believed to be better armed and equipped than the regular military. In recent years, the Guard has also amassed a wide network of economic and political power. The tensions between the Revolutionary Guard and judicial authorities suggests possible rivalries emerging in the highest levels of Iran's leadership as it tries to regain balance after the worst internal unrest since the 1979 Islamic Revolution. Such internal rifts could pose serious complications for Supreme Leader Ayatollah Ali Khamenei, who has previously relied on near seamless unity at the top to enforce policies and control. The tensions come as Iran presses forward with a mass trial of more than 100 prominent reformist figures, opposition activists and others accused of offenses ranging from rioting to spying and seeking to topple the country's Islamic rulers through what they call is a "soft overthrow." The trial, which has included televised confessions that rights groups say are likely extracted through pressure, is the government's latest attempt to crush the opposition. Iran's most senior dissident cleric, Ayatollah Hossein Ali Montazeri, has also compared the mass trial and the public confessions to the tactics of former Soviet dictator Josef Stalin, former Iraqi dictator Saddam Hussein and other authoritarian rulers. US Secretary of State Hillary Rodham Clinton said in a TV interview broadcast Sunday that the Obama administration continued to back the opposition, as she said it did in the days just after the vote. "We're continuing to speak out and support the opposition," she said on CNN's "Fareed Zakaria GPS" program. Clinton said she was appalled at the treatment of detainees brought to trial. "It is a show trial. There is no doubt about it," she said. "And it is a sign of weakness. It demonstrates, I think, better than any of us could ever say, that this Iranian leadership is afraid of their own people, and afraid of the truth and the facts coming out." During a second hearing in the trial on Saturday, defendants talked about helping a shadowy monarchist-linked group planning a terror campaign to destabilize the country as well as meeting with US intelligence operatives in northern Iraq, state-run Press TV reported. Mohammad Reza Ali Zamani said he met with a US intelligence agent called "Frank" in Irbil, the capital of the Iraqi Kurdish autonomous region, and received money and a phone from him in return for information on the Iranian government and student movements.