Gaza City Hamas said on Thursday that one of its members, Kamal Husni Ghanaja, was killed in his Damascus home in what the Palestinian Islamist group described as a “cowardly murder”.

In a statement in Gaza, Hamas did not immediately accuse Israel, its long-time enemy, of involvement in his death, saying only that it had launched an investigation “to identify the party behind the deplorable crime”.

A Hamas source in Gaza said “there were marks of torture” on Ghanaja’s body. The organisation, which rules the Gaza Strip, did not disclose his role in the movement but said he “spent his life working for the sake of God” within its ranks.

Damascus has served as a base for Hamas’s leadership in exile but many of the group’s top officials and their families in the city have left Syria during its past 16 months of conflict. One Hamas source described Ghanaja as a mid-level military official.

Asked about reports of Ghanaja’s death, Israeli Defence 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.”

Israel’s Mossad intelligence service is widely believed to have been behind the assassination in Dubai in 2010 of Mahmoud Al Mabhouh, a top Hamas commander. Israel, sticking to a policy of “ambiguity” on Mossad operations, refused to confirm or deny its agents killed him