One more Palestinian refugee has died under torture in Syria’s state-run prisons, according to a London-based human rights watchdog.

The Action Group for Palestinians of Syria (AGPS) has documented the death of of a Palestinian refugee in Syrian prisons. His name has been kept secret over security concerns as his family lives in Damascus.

The family was updated on the refugee’s death on March 1. The victim was a resident of Yarmouk Camp for Palestinian refugees, in Damascus.

AGPS has recorded the death of over 620 Palestinian refugees under torture in Syrian government penitentiaries, among them minors and elderly detainees.

AGPS believes the number is far higher due to the gag orders enforced by the Syrian regime on the detainees’ fates and names, along with the reluctance of the casualty’s families to reveal the names of their deceased or missing relatives for fear of retaliation.

Most of the victims’ bodies have been withheld by the Syrian authorities, which is prohibited under international law except in cases where pillage and mistreatment are feared to occur.

The Fourth Geneva Convention, the Hague Convention, and the Rome Statute consider the despoliation and mistreatment of dead bodies war crimes.