Syria's security forces have arrested hundreds of people arbitrarily since pro-democracy protests erupted a month ago and subjected them to torture and ill-treatment, a Human Rights Watch report said on Friday.
The forces, which include al-mukhabarat (secret police), also detained and tortured rights campaigners, writers and journalists who have reported or supported the protests against President Bashar al-Assad's rule, the international New York-based organisation said.
"There can be no real reforms in Syria while security forces abuse people with impunity," Joe Stork, deputy Middle East director at Human Rights Watch, said in a statement.
"By silencing those who write about events, Syrian authorities hope to hide their brutality. But their crackdown on journalists and activists only highlights their criminal behaviour," he added.
The group said at least seven journalists were detained.
There was no immediate comment from the Syrian authorities, who have come under mounting Western criticism for using force to put down protests that have spread across several parts of Syria since they erupted in the southern city of Deraa on 18 March . An estimated 200 people have been killed.
Human Rights Watch interviewed 19 freed detainees, including three teenagers. All but two detainees said mukhabarat operatives beat them and that they witnessed dozens of other detainees being beaten or heard screams of people being beaten.
"In addition to three children interviewed by Human Rights Watch, witnesses reported seeing children detained and beaten in the facilities where they were held," the report said.
Many described how they were tortured with electro-shock devices, cables, and whips and held in overcrowded cells while being deprived of sleep, food, and water. Several were blindfolded and handcuffed the entire time, the report said.
A Syrian writer told Human Rights Watch he was "kidnapped" off a Damascus street after he commented critically about the government's response to the protests in the media.
"I saw a white unmarked van on the street, and when I came directly beside it, the sliding door opened and three big men grabbed me," he told Human Rights Watch.
His captors, who were State Security agents, beat and kicked him on the way to and during interrogation, using a whip, the report said. It added that a non-Syrian Arab journalist said that he was also beaten during interrogation.
Assad has ordered the release of detainees who have been arrested during the protests except those who committed crimes "against the nation and citizens".
A human rights lawyer said several hundred have been released but they were just "a drop in the ocean" compared with the thousands of political prisoners in Syria, whose numbers have swelled since the protest began.
The report said most detainees interviewed were forced to sign confessions without being allowed to read them, and sign pledges not to participate in protests.
"None were allowed to have any contact with relatives or lawyers ... and their families were not informed of their whereabouts. One, a 17-year-old, could hardly move -- he needed assistance sitting down and standing up," the report said.
Human Rights Watch said it reviewed video footage showing evidence of severe beatings to the face and arms of a 12-year-old from Douma, a suburb of Damascus.
The report quoted a protester from Tel, a town just north of Damascus, describing his experience at a State Security branch on Baghdad Street.
"They lined us up in the corridor along the wall, and beat us. Then they dragged us to the basement -- I lost consciousness for some time, they beat me very hard on my head," the freed protester was quoted as saying.
"I was hooded at the time," he said. "They first kept all 17 of us in one room, and took (us) out for interrogations from there -- they beat us with a cable, and accused us of being Israeli and Lebanese spies."