BEIRUT, 21 May — The elder son and heir apparent of Palestinian activist Ahmad Jibril was killed yesterday in a Beirut car-bombing which his group promptly blamed on Israel and vowed to avenge. Jihad Jibril, a senior leader in Lebanon of his father’s Syrian-based Popular Front for the Liberation of Palestine-General Command (PFLP-GC), was blown to pieces when he started his car, detonating explosives under the seat, police said.

“Mossad managed this time to assassinate my son after having tried in vain four times to do it,” Ahmad Jibril told reporters at his headquarters in Damascus, referring to the Israeli intelligence service, as he received condolences.

Another PFLP-GC official told reporters in the Syrian capital on condition of anonymity that “the Zionist enemy is the first suspect and we are going to retaliate because they killed one of our military leaders.” But Israeli Foreign Ministry spokesman Emmanuel Nachshon dismissed the accusations as “utter nonsense.”

Police said that some two kilos of explosives had been placed in the car, wrecking the white Peugeot 505 in the blast, which happened only meters from a police barracks in west Beirut’s Mama Street, adjoining Mar Elias Boulevard.

Jihad, who was born in 1964, is scheduled to be buried in Syria tomorrow. His body was handed over to his family later in the evening, and mourners fired in the air as they bore it, wrapped in a Palestinian flag, through the Palestinian refugee camp of Burj Al-Barajneh in the suburbs of Beirut.

In another development, Israel said yesterday it will speed up construction of a fence separating it from the West Bank after two Palestinian bombers killed themselves and three Israelis within a space of 24 hours, shattering a growing sense of calm. Defense Minister Binyamin Ben Eliezer met mayors of several Israeli border towns to discuss the construction, his ministry said in a statement in Jerusalem after a second Palestinian blew himself up at a bus stop near Afula in the north.

In the meeting with the mayors, Ben Eliezer “confirmed he intends to proceed with a continuous security barrier, notably including a fence and electric equipment, along the 350-kilometer demarcation line,” the ministry said.

Meanwhile, Arab League chief Amr Moussa threatened in a newspaper interview published yesterday that Israeli troops must pull back to their positions before the outbreak of the 20-month Palestinian intifada, or there will be no Middle East peace conference this summer.

“All of us are in agreement on the fact that this conference must not be held as long as Israel occupies Palestinian towns and villages. They must withdraw to the lines before September 2000 in order for this meeting to become possible,” he told the London-based Al-Hayat daily.