Gaza - The radical Hamas movement Friday demanded the release of Hamas prisoners in the West Bank in return for letting rival Fatah members leave Gaza to attend a congress in Bethlehem.

Palestinian President Mahmoud Abbas' Fatah Party is expected to elect a new leadership at its sixth General Assembly in the West Bank city of Bethlehem on August 4.

Some 1,550 members are expected to attend, including 400 from the impoverished Gaza enclave, which has been ruled by Hamas since 2007.

But Hamas strongman Mahmoud al-Zahar told reporters in Gaza that Hamas prisoners detained by Fatah in West Bank jails would have to be released before the Gaza- based Fatah delegates can leave.

Egypt has asked Hamas to let the Fatah members attend the assembly, the first since 1989 when it was held in Tunis.

"Fatah had asked Egypt's mediation to let 400 Gaza members leave to West Bank to join the conference in Bethlehem. We say charity for charity and sin for sin," said al- Zahar, a reference to the arrest of Hamas members.

Hamas says Abbas' security forces are holding around 800 of its members in West Bank jails. Fatah says Hamas security forces have detained hundreds of its members in Gaza.

Egypt has called on Fatah and Hamas leaders to join other less influential factions in Cairo on August 25 to sign a reconciliation agreement hammered out during seven rounds of difficult dialogue.(dpa)