1 February 2017: Syrian children play in Aleppo's previously rebel-held neighbourhood of Jibreen George Ourfalian/AFP

Human rights abuses and torture are widespread in Syria's prisons under the Assad regime, report eyewitnesses who claim they have been tortured while incarcerated.

An eyewitness spoke of seeing children around four years in age struck until their hands were bleeding. She also heard the sounds of men being tortured and killed, saying: "Those who were tortured for a while would lose their voice. And at first we didn't know, but then we understood that whoever's voice faded away or disappeared, that means he's dead."

A 15-year-old girl also reported that many women and children were imprisoned and received harsh treatment. "There were children with their mothers, and even the children were tortured. They would beat them and make them stand against the wall as punishment," she said.

The teenager described the treatment she and her father received when they left rebel-held areas, and were moved into government-controlled areas of Aleppo and held in jail.

"They held us at the checkpoint and arrested my father," she said. "They made him kneel on the ground then they took him inside to the detention room. They tortured him with a knife.

"They took me with him and said: 'You're a terrorist and you're a sniper.' I denied it but they said there is a report and we're sure of this information. To scare me they had my father kneel on the floor and grabbed him by his hair," she told Sky News.

The women were eventually released after several months as part of prison exchanges.

A report by Amnesty International states that up to 13,000 people, mostly opposed to the government were hanged at the Saydnaya prison.

Lynn Maalouf, Deputy Director for Research at Amnesty International said: "We demand that the Syrian authorities immediately cease extrajudicial executions and torture and inhuman treatment at Saydnaya Prison and in all other government prisons across Syria."

Syrian President Bashar Assad refuted the allegations in an interview with Yahoo News, saying that Amnesty International had fabricated evidence to discredit him. "You can forge anything these days," Assad said regarding the report. "We are living in a fake news era."