BETHLEHEM (Ma'an) -- A Hamas leader was assassinated in Damascus on Wednesday night, a member of the party's politburo said.
Izzat al-Rishq wrote on his Facebook page that Kamal Ghanaja, also known as Nizar Abu Mujahed, was killed in his home in the Syrian capital.
Hamas is investigating the crime, al-Rishq said, adding that the "cowardly" murder would not go unpunished.
A Hamas source in Gaza said "there were marks of torture" on Ghanaja's body.
A Hamas official in Lebanon told Agence-France Presse that the group suspected Israel's Mossad of killing Ghanaja.
Ghanaja had worked as an aide to Mahmoud al-Mabhouh, a senior Hamas leader who was shot dead in a hotel room in Dubai
Israel's Mossad intelligence service is widely believed to have been behind the assassination of al-Mabhouh. Sticking to a policy of "ambiguity" on Mossad operations, Israel refused to confirm or deny its agents killed him.
Asked about reports of Ghanaja's death, Israeli Defense Minister Ehud Barak told Israeli Army Radio: "He was not really personally familiar (to me). According to all the background published, he was no saint and I don't want to add anything or comment about this incident."
Several websites affiliated to the opposition to President Bashar Assad blamed the Syrian regime for Ghanaja's killing and said Assad's forces murdered the Hamas leader as a message to the movement not to reject its long-time ally.
Hamas' politburo moved to Damascus in 1999 after it was expelled from Jordan, but the party quietly quit the Syrian capital amid the bloody revolt against Assad. In February, Hamas leaders publicly denounced Assad and declared their support for Syrian rebels.Reuters contributed to this report.