Salaheddin Brigades claims to have eliminated Mussa Arafat at his home in Gaza City.
Mussa Arafat, a military advisor to Palestinian leader Mahmud Abbas and a cousin of the late Yasser Arafat, was shot dead by gunmen at his home in Gaza City on Wednesday.
Abbas convened an emergency meeting of his national security council to discuss how best to assert control over the lawless Gaza Strip with his forces preparing to take control from Israeli troops in little over a week.
Arafat's assassination, just hours after a Palestinian teenager was killed by Israeli troops in southern Gaza, underscored the security chaos and mammoth task facing the Palestinians once Israeli troops leave by mid-September.
Israel's top brass are calling for soldiers to be recalled from Gaza immediately, saying every further day endangers their lives amid daily clashes with youths on the borderlines of the former Jewish settlements.