CAIRO  - The family of former Egyptian president Anwar Sadat has threatened to sue the Iranian producers of a documentary film portraying his 1981 assassination as the killing of a traitor by a martyr. The documentary, entitled "Assassination of a Pharaoh", has already been shown on Iranian television, the Al-Masry al-Youm newspaper reported on Sunday. The film, broadcast "in honour of the martyrs of the Islamic renaissance", deals with "the revolutionary assassination of the treacherous Egyptian president at the hands of the martyr Khaled Islambouli," the Paper said. Islambouli was one of the soldiers who shot Sadat dead at a military parade in Cairo on October 6, 1981. He was hanged for the killing in 1982 and subsequently had a Tehran road named after him. "The producers should have asked for the family's authorisation before making the film," said Sadat's daughter, Roqeya. "Such slander will receive a strong response." The Iranian film says Sadat was killed for signing the 1978 Camp David Accords that led to a 1979 peace treaty with Israel, the first by an Arab country. "Making this film is a low attempt to tarnish the image of the man and falsify history," said Sadat's nephew and MP Talat. The newspaper quoted a leader of former group Gamaa Islamiya, one of those charged with Sadat's killing, as saying: "Sadat was a great man (but) Khaled Islambouli thought he was doing right by killing him."