Mustafa Khalil, a former Egyptian prime minister who was an architect of the 1979 Camp David peace treaty between Egypt and Israel, has died, the state news agency reported Sunday. He was 88. MENA said Khalil died late Saturday in a Cairo hospital, where he was being treated for an unspecified illness. Khalil - then secretary-general of the ruling Arab Socialist Union party - accompanied late president Anwar Sadat in his historic visit to Jerusalem in November 1977. The visit paved the way for the negotiations mediated by then-US President Jimmy Carter. Khalil, who serves as prime minister from 1978-1980, then headed the Egyptian team in negotiations with the Israelis at Camp David, which ended with the 1979 peace deal, the first between an Arab nation and Israel. "Khalil contributed in serving the country for over 50 years and took part in making peace and building the basis of development," former UN Secretary-General Boutros Boutros-Ghali told MENA in reaction to Khalil's death.