The king of Bahrain has promised reforms to prevent abuses by security forces, after an independent report about a crackdown on protests said authorities had used "excessive force".
King Hamad expressed "dismay" at the findings and vowed to ensure "those painful events won't be repeated".
The much-awaited report into the events in February and March said a number of detained protesters had been tortured.
More than 40 people died in the unrest, which some officials blamed on Iran.
Bahrain has a majority Shia Muslim population and the violence has fuelled anger against the ruling Sunni royal family and political elite.
More than 1,600 people have been arrested during the protests, which have continued sporadically since the peak of the unrest eight months ago.
'No Iran link'
The summary of the 500-page report was presented by the Bahrain Independent Commission at King Hamad's palace in Manama on Wednesday.
The head of the commission, Professor Cherif Bassiouni, said investigations had found officials "used excessive force". Many detainees were subjected to "physical and psychological torture", he said.
Inmates, he added, had been blindfolded, whipped, kicked, given electric shocks and threatened with rape to extract confessions.
Prof Cherif said the evidence seen by the commission "did not prove a clear link between the events in Bahrain and Iran".
He also stressed that it was a "unique and historic" event - the first time a state in the region had voluntarily and without international pressure investigated unrest in its own country.
Prof Cherif is a former UN human rights lawyer. The other commission members are all non-Bahrainis.
The inquiry interviewed more than 5,000 people, including hundreds who say they were tortured in prison.
The king, Sheikh Hamad bin Isa Al Khalifah, heard the report sitting on a red and gold throne in front of an audience of nearly 1,000 people.
He stressed that he never again wanted to see Bahrain paralysed by "intimidation and sabotage", adding: "Nor do we want, ever again, to discover that any of our law enforcement personnel have mistreated anyone."
He promised to reform Bahrain's laws to protect freedom of speech and other basic rights.
"We do not want ever again to see civilians tried anywhere else but in ordinary courts," he said.
The monarch said the report opened "a new page" in Bahrain's history, promising to sack those officials who had abused their power.
If the king acts to change the way the country is run, then the outcome could be positive, the BBC's Rupert Wingfield-Hayes in Bahrain reports.
If not, then more violence is likely to lie ahead, our correspondent says.