Prominent Palestinian figure George Habash, the founder of the radical Popular Front for the Liberation of Palestine (PFLP), died in Jordan on Saturday, the Palestinian government said.
Habash, who was 81, founded the PFLP in 1968.
Habash, a longtime rival of Yasser Arafat, led the PLO's second-largest faction which pioneered airliner hijackings.
"He had a severe heart attack and he died instantly," said Leila Khaled, a member of the Palestine National Council and a leading member of the PFLP.
Khaled spoke by telephone from Jordan Hospital in Amman, where she said Habash died at 8:15 p.m. Saturday.
The PFLP's spokesman in Damascus, Maher al-Taher, confirmed Habash's death. The former guerrilla leader had been living in Amman since 1992, al-Taher said.
Habash and his group gained notoriety for the hijackings in 1970 of four Western airliners over the United States, Europe, the Far East and the Persian Gulf. The aircraft were blown up in the Middle East after passengers and crews disembarked.
The group also was responsible for gunning down 27 people at Israel's Lod airport in May 1972.
Habash, an American-educated physician, launched the Popular Front in December 1967, six months after the Arabs lost the West Bank, Gaza Strip and Golan Heights to Israel.
Habash opposed the interim peace agreements with Israel, in part because they did not require Israel to stop settlement construction. Throughout his life, he supported the use of violence against Israel, arguing that Israel would not make the concessions required for a peace agreement.
Palestinian President Mahmoud Abbas's office declared a three-day mourning period for Habash.