Beirut ? A car bomb Friday killed a leader of Islamic Jihad, a Palestinian militant group whose suicide bombers have defied a truce with Israel and killed 34 people in the last year, including an American.

Islamic Jihad blamed Israeli intelligence and vowed to retaliate for the attack, which killed its leader in southern Lebanon, Mahmoud Majzoub, and his brother, Nidal.

Lebanon’s Prime Minister Fuad Saniora condemned the killings and pledged to “exert all efforts to punish the aggressors.” He indicated that Israel was the primary suspect.

Islamic Jihad’s representative in Lebanon, Abu Imad Rifai, vowed a harsh response and said it would come from “the brothers inside,” meaning Islamic Jihad members in Gaza or the West Bank.

In Israel, military officials said they had heard of the bombing in media reports but had no additional information.