People detained by the Syrian authorities are being systematically and routinely tortured, an Amnesty International report alleges.
The rights group says officials are using techniques including suspending and then beating detainees with fists and rifle butts.
Many of those from whom Amnesty gathered testimony said children were among the torture victims.
Syrian authorities have denied torturing opponents of the government.
"The testimonies we have heard give disturbing insights into a system of detention and interrogation which, a year after protests began, appears intended primarily to degrade, humiliate and terrify its victims into silence," said Ann Harrison of Amnesty's Middle East and North Africa Programme.
Amnesty said its report, entitled I Wanted to Die, was based on testimony gathered during a visit to Jordan in mid-February, during which its researchers spoke to dozens of people who had fled Syria.
Some 25 of them had been tortured or ill-treated in detention, Amnesty says.
International journalists face severe restrictions on reporting in Syria, and it is hard to verify such reports.
Amnesty said the ill treatment of detainees would start from the moment they were arrested, escalating into a lengthy beating when they arrived at the detention centre itself.
"They suffered prolonged and repeated beatings with fists and various instruments including sticks, rifle butts and electric cables, as well as kicks," the report reads. Detainees were then often stripped and left exposed to the elements for 24 hours.
The report also documents specific torture methods used - including the dulab, where the victim is forced into a tyre which is hoisted up so they can be beaten on the feet.
Another is known as shabeh, where the victim is suspended from a raised hook or door frame, so their feet hang just above the ground. Electrocution - where an inmate is soaked and an electric charge is applied to a water-covered floor - was also documented.
Amnesty is urging the Syrian authorities to stop carrying out arbitrary arrests and detaining those who peacefully express their opposition to the government, and to cease the use of torture and other ill-treatment.
It is also calling for the UN Security Council to refer the situation in Syria to the International Criminal Court to investigate alleged crimes against humanity.
The report comes as the UN announced that it would soon deploy human rights monitors to countries bordering Syria to collect eyewitness testimony on "atrocities" committed in the country.
Last month, independent UN investigators led by Paulo Pinheiro said that Syrian forces committed crimes against humanity including murder and torture on orders from the "highest level" of the government of President Bashar al-Assad.