Hundreds of prominent cultural figures have signed an open letter urging Israel to release Marwan Barghouti, the most prominent Palestinian detainee in Israeli custody.

Barghouti has been in an Israeli prison since the early 2000s. He is a prominent member of Fatah, the Palestinian political faction that dominates the Palestinian Authority, which governs limited parts of the occupied West Bank, Al Jazeera reported. 

He is serving five life sentences plus 40 years on murder and attempted murder charges, which he has consistently denied.

“We express our grave concern at the continuing imprisonment of Marwan Barghouti, his violent mistreatment and denial of legal rights whilst imprisoned,” read a statement signed by more than 200 prestigious names.

The list includes actors Tilda Swinton, Josh O’Connor and Mark Ruffalo; writers Margaret Atwood, Zadie Smith and Annie Ernaux; and musicians Brian Eno, Sting and Paul Simon.

Palestinians had called for Barghouti to be released as part of the Gaza ceasefire agreement between Israel and Hamas, but Israel refused to free him.