BEIRUT

Rights activists visiting abandoned government prisons in the first Syrian city to come under rebel control have found torture devices and other evidence that detainees were abused there, Human Rights Watch said in a report Friday.

Raqqa, in eastern Syria, was overrun in late February by rebels fighting to topple President Bashar Assad. The rebels facilitated the New York-based group’s access to facilities that had belonged to a government security agency and military intelligence in late April.

Human Rights Watch said its researchers found physical evidence that Syrians were tortured, including with a device which former detainees said was used to stretch or bend victims’ arms and legs. The group also found documents indicating Raqqa residents were detained for legal actions such as demonstrating or helping the injured.

Rights groups and opposition activists have long claimed civilians have been detained arbitrarily, tortured, and sometimes have disappeared since the uprising against Assad’s regime began. HRW’s findings appear to be one of the largest finds of physical evidence bolstering those claims to date.

“The documents, prison cells, interrogation rooms, and torture devices we saw in the government’s security facilities are consistent with the torture former detainees have described to us,” said Nadim Houry, deputy Middle East director for HRW.

HRW has been documenting abuses on both sides of Syria’s civil war during the 26 months of conflict.

The group says abuses by the Assad regime remain far more deadly, systematic and widespread, including attacks on civilians with indiscriminate battlefield weapons such as widely banned cluster bombs. But the rights group also says rebel abuses have increased in frequency and scale in recent months.

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