Two leading Islamic militants jailed over the 1981 killing of Egypt's President Anwar Sadat have been released after 24 years behind bars, prison officials and a lawyer said Tuesday. Nageh Ibrahim and Fouad el-Dawalibi, both founding members of Al-Gamaa al-Islamiyya, once Egypt's largest Islamic militant group, were released last Wednesday, the prison officials said on condition of anonymity as they were unauthorized to speak to the media. The two men, believed to be in their early 50s, were convicted for taking part in Sadat's killing during a Cairo military parade on Oct. 6, 1981. It was not immediately clear why they were released, but leading Islamist lawyer Montasser el-Zayat said Tuesday that he believed the men were freed as part of a truce between the militant group and the government. Ibrahim and el-Dawalibi were among the architects of a truce with the government announced in 1997 and have advocated moderation and peace in numerous books the group published three years ago. Al-Gamaa al-Islamiyya, or Islamic group, in its campaign to overthrow the government during the 1990s killed more than 1,000 people, mostly militants, tourists and police. The group also opposed Egypt's 1979 peace deal with Israel that Sadat brokered.