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The 38-year-old son of Palestinian guerrilla leader Ahmed Jibril was killed Monday in a Beirut car bombing. Jibril's radical group blamed Israel and vowed retaliation.

Israel denied any connection to the blast, which happened at midday on a street off the busy shopping area of Corniche Mazraa in Beirut's Muslim sector.

Jihad Jibril was a senior commander of military operations in Lebanon for his father's faction of the Popular Front for the Liberation of Palestine-General Command, a small Syrian-based group that is on the State Department list of terrorist organizations for its attacks on Israelis.

In one of its most notorious attacks, a PFLP-GC guerrilla landed a hang-glider near a military outpost in northern Israel in November 1987 and killed six soldiers with hand grenades and a machine gun before being killed himself.

The group has rejected peace with Israel and opposed the Oslo process that started negotiations between Israel and the Palestinians after secret talks that concluded in 1993. Jibril and Palestinian leader Yasser Arafat have been enemies for at least two decades.

Following Monday's explosion, a somber-looking Ahmed Jibril accepted condolences at his office in Damascus, Syria, but did not comment.

When asked who was responsible for the assassination, Talal Naji, an aide to Ahmed Jibril, said only: "Israel alone." Another aide pledged to retaliate.

"The response for the assassination will be on the same scale but the time and circumstances will decide the nature of the operation and its timing," said Omar Shehabi, a comrade of Jihad Jibril on the leadership's executive committee.

"He was targeted because he was the son of Ahmed Jibril. He was a target of America and Israel because of his marks on the (Palestinian) struggle in Lebanon and the occupied territories."

Israel denied involvement.

Yaden Vatikay, an adviser to Israeli Defense Minister Binyamin Ben-Eliezer, said: "The defense minister says Israel is not connected and to stop blaming Israel."

Last month, the senior Jibril warned that suicide bombings against Israelis would continue in retaliation for Israeli military attacks.

However, the PFLP-GC has not claimed responsibility for suicide bombings since the latest violence erupted in September 2000. Last month, the PFLP-GC and two other rival groups each claimed to have blown up an Israeli tank in the Gaza Strip.

But the PFLP-GC was accused by Lebanese authorities of firing rockets across the Lebanese border into Israel in April at the height of the West Bank offensive and of seeking to launch more attacks on the Jewish state. Nine Palestinians who Lebanese authorities said belonged to the PFLP-GC have been arrested on charges of illegal possession of weapons and threatening national security.

Last year, Jibril acknowledged that his group had sent to the Palestinian territories a weapons shipment that was seized by the Israeli navy – and he promised more to come.

A Lebanese police official at the scene, speaking on condition of anonymity, said Monday's explosion was caused by a small stick of plastic explosive that was placed under the driver's seat of the Peugeot sedan.

The blast wrecked the car, shattering its windows and turning its front section into a twisted heap. Its white rear door had turned red with the victim's blood and flesh was scattered for a few yards around the car.

The blast also damaged neighborhood shops and parked cars but, apart from the driver, there were no other casualties.

PFLP-GC officials in Damascus said Jihad Jibril's body would be taken to Damascus for a funeral Tuesday.

Jihad Jibril was commander of military operations in Lebanon and a member of the PFLP-GC's executive committee leadership. He had taken military courses in Libya and had the rank of a lieutenant colonel. In addition to his military activities, he was in Lebanon studying law at a Beirut university. He is survived by his wife and two sons, 10-year-old Ahmed and 6-year-old Ali.

During the 1975-90 Lebanese civil war, car bombs were frequent in Lebanon as a way to settle scores among the various warring groups. But they had become rare as the government restored its authority across the country.

Most recently, a January car bomb killed Elie Hobeika, a former Cabinet minister and ex-militia leader, along with three bodyguards.