The Office of the High Commissioner for Human Rights said in a report released Monday that it had interviewed individuals who spent time in detention facilities in Syria. It did not identify them by name.
It said the young woman reported that she had been tortured during repeated nightlong interrogation sessions. The report does not say where she was detained but notes that "on one occasion, a security officer took her and another woman to a room where they were raped."
Another victim, according to the OHCHR, was a 30-year-old university student who said he had been beaten, had his beard pulled out in clumps, had his feet burned and had his toenails torn off with pliers at a Syrian air force intelligence facility in Hama, where he was interrogated daily for more than a month.
"I urge the government and armed opposition groups in Syria to immediately halt the use of torture and ill treatment and to release all those who have been arbitrarily detained in conditions that clearly breach international human rights standards," said High Commissioner Navi Pillay.
"Those detained must be treated humanely," she said.
The abuses cited in the report were committed by government forces and some opposition groups, the agency said. Government forces appeared to be responsible for several cases detailed by the U.N. News Center. The report also details torture techniques of state authorities though not those of opposition forces.
"Detainees [in governmental facilities] are routinely beaten and humiliated for several hours by the guards in what has come to be known as the 'reception party' " upon their arrival at detention facilities, it says.
"Men, women and children have been routinely picked up from the street, their homes and workplaces, or arrested at government-manned checkpoints," it says. "Many are activists – often students – as well as lawyers, medical personnel and humanitarian workers, and some just happened to be in the wrong place at the wrong time."
The OHCHR paper says reports of torture by opposition groups appear to be on the rise since 2013, particularly in the restive Raqqa area in northern Syria. The government has lost control of parts of northern and eastern Syria to Islamist rebels and foreign militants during the 3-year-old conflict.
According to the U.N. News Center, "documenting allegations against such groups is particularly challenging due to constantly evolving alliances and changes in memberships, power structures and areas under their control."
Victims' testimony, according to the report, suggests that activists attempting to document human rights violations and those considered to be pro-government or affiliated with other armed opposition groups are the ones most likely to be tortured by militants.
The report cites cases of individuals who died in detention in conditions that suggest torture was the cause.
More than 100,000 people are believed to have been killed in the Syrian conflict, and millions of people have been forced from their homes.