A special commission probing Bahrain's March crackdown on Shiite-led democracy protests said on Wednesday that police used "excessive force" and tortured detainees, prompting King Hamad to vow reforms.
The findings announced by the head of the Bahrain Independent commission for Inquiry, Cherif Bassiouni, revealed that security forces "used excessive force" and "many detainees were tortured."
King Hamad commissioned the report to investigate allegations of government misconduct and human rights abuses against protesters, democracy activists, and opposition figures.
"We will introduce and implement reforms that would please all segments of our society," he said.
In Washington, the White House said it would closely follow the government's actions.
"It is now incumbent upon the government of Bahrain to hold accountable those responsible for human rights violations and put in place institutional changes to ensure that such abuses do not happen again," spokesman Jay Carney said in a statement.
King Hamad expressed "dismay" at the mistreatment of Shiite detainees.
"We do not tolerate the mistreatment of detainees and prisoners. We are dismayed to find that it has occurred, as your report has found," he said.
Responding earlier, an official spokesman said the government accepts the criticisms.
"We took the initiative in asking for this thorough and detailed inquiry to seek the truth and we accept it."
The statement said the government regretted the "mistreatment of detainees, as well as five deaths as a result of torture."
The report acknowledged the commission did not find proof of an Iran link to the unrest, dispelling widespread allegations by Sunni Gulf leaders that Tehran played a role in instigating the mainly Shiite protests.
"Evidence presented to the commission did not prove a clear link between the events in Bahrain and Iran," said Bassiouni.
However, King Hamad insisted that Iranian propaganda was a factor.
"Iran's propaganda fuelled the flames of sectarian strife -- an intolerable interference in our internal affairs from which Bahrain has suffered greatly," he said.
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Al-Wefaq, the main Shiite opposition group in Bahrain, called for a "national salvation government," saying the report "confirmed systematic, serious and deliberate violations... which means that the current government that committed these crimes should be removed."
It also said the report "revealed clearly that the Bahraini revolution was national and that Iran had nothing to do with it."
Leading Al-Wefaq ex-MP Khalil al-Marzouq told AFP "the king should act seriously," adding that his promise of reform was mere "repetition."
The mass demonstrations which rocked the Sunni-ruled kingdom earlier this year were violently crushed by government forces using live ammunition and heavy-handed tactics.
The report said the death toll from the unrest reached 35, including five security personnel and five detainees who were tortured to death while in custody. Hundreds were also injured.
The findings, which studied events in February and March, said that 11 other people were killed later. The commission concluded that a total of 2,929 people were detained during the protest movement, and at least 700 remain in prison.
The 500-page report said there was also evidence that Sunni Muslims "were the target of... humiliation, physical assaults, and attacks against their property."
Recommendations included opening the security forces to recruit Bahrainis from all communities, referring to Shiites, commuting death sentences arising from the unrest, and compensating families of the dead.
It also recommended establishing a national commission of government, opposition and civil society representatives to follow up and implement the recommendations.
It called for an impartial mechanism to determine the accountability of those in government who have committed unlawful or negligent acts resulting in the deaths, torture and mistreatment of civilians.
Amnesty's Bahrain researcher told AFP that the London-based human rights watchdog welcomed the commission's recommendations and agreed with its findings.
"We felt the report was accurate... in general," said Said Boumedouha."There are also some very good recommendations," he said, adding that the real challenge ahead is implementing reform.
Boumedouha said the commission came to many of the same conclusions as Amnesty, particularly on the presence of "widespread torture... and grossly unfair trials."
In March, security forces boosted by some 1,000 Gulf troops crushed the month-long uprising in Manama's Pearl Square, epicentre of the anti-government movement that apparently took the lead from Tunisian and Egyptian protests.
"The commission did not find any proof of human rights violations caused by the presence of the Peninsula Shield forces," Bassiouni said.
Iran and fellow Shiites across the Arab world had slammed Bahrain for calling in forces from fellow Sunni monarchies, claiming that the Saudi-led force was used against Shiite Bahrainis.