More than 17,000 detainees have died in the government's custody over the past five years as a result of torture, diseases and other causes, according to a report released Thursday by the London-based Amnesty International.
The report, titled "'It breaks the human," includes interviews with 65 torture survivors who described abuse and inhuman conditions in security branches operated by Syrian intelligence agencies and in Saidnaya Military Prison, near Damascus.
It said common methods of torture included forcibly contorting the victim's body into a tire and flogging on the soles of the feet. The authorities also used electric shocks, rape and sexual violence, the pulling out of fingernails or toenails, scalding with hot water and cigarette burns.
"The catalogue of horror stories featured in this report depicts in gruesome detail the dreadful abuse detainees routinely suffer from the moment of their arrest, through their interrogation and detention behind the closed doors," said Philip Luther, director of Amnesty International's Middle East and North Africa program.
"This journey is often lethal, with detainees being at risk of death in custody at every stage," he said. He urged the international community to bring these abuses to the top of the agenda in talks with both the government and armed groups.
The abuses date back to the start of the Syrian uprising against President Bashar Assad in March 2011. The government's harsh crackdown on dissent and the rise of armed opposition groups eventually ignited a civil war that has killed more than 250,000 people, displaced half the country's population and generated more than 4.8 million refugees.
The Amnesty report highlights new statistics from the Human Rights Data Analysis Group, or HRDAG, an organisation that uses scientific approaches to analyse human rights violations, which indicate that 17,723 people died in custody across Syria between March 2011 and the end of 2015.
"With tens of thousands of people forcibly disappeared in detention facilities across Syria, the real figure is likely to be even higher," Amnesty said.