The Israeli military said Ismail Baz, killed in a strike on a car near the southern town of Ain Ebel, was the commander of Hezbollah’s coastal sector and was involved in planning rocket and anti-tank missile attacks on Israel.
Hezbollah issued a statement mourning Baz’s death but did not elaborate on his role in the organisation.
Separate Israeli strikes on two vehicles near the southern town of Chehabiyeh killed at least two Hezbollah members, a security source and a civil defence official claimed.
Hezbollah and Israel have traded fire in parallel to the Gaza war in the most serious hostilities since they fought a major war in 2006.
The fighting has claimed the lives of at least 370 Lebanese, including more than 240 Hezbollah fighters and 68 civilians, according to a Reuters toll and has fuelled concern about the potential for further escalation between regional enemies.
Eighteen Israelis, including soldiers and civilians, have been killed.