Israel's army said it had killed the cleric tipped to succeed slain Hezbollah leader Hassan Nasrallah in an air strike on Beirut three weeks ago that targeted commanders of the Iran-backed militant group.
Hezbollah has not issued a statement about the Israeli claims to have killed Hashem Safieddine.
"It can now be confirmed that in an attack approximately three weeks ago, Hashem Safieddine, the head of Hezbollah's Executive Council, and Ali Hussein Hazima, the head of Hezbollah's Intelligence Directorate, were killed along with other Hezbollah commanders," the Israeli army said in a statement Tuesday.
The army said the air force had hit Hezbollah's main intelligence headquarters in the southern Beirut suburb of Dahiyeh, Hezbollah's stronghold in the Lebanese capital, and that more than 25 Hezbollah militants were present at the time.
Longtime Hezbollah leader Nasrallah was killed on September 27 in an Israeli air strike on Beirut's southern suburbs.
Safieddine, tipped to succeed his distant cousin as leader of the Lebanon-based group, had been out of contact since Israeli strikes on Beirut weeks ago, a high-level Hezbollah source said at the time.
"We have reached Nasrallah, his replacement and most of Hezbollah's senior leadership", Israeli army chief Lieutenant General Herzi Halevi said in a statement after the confirmation of Safieddine's death.
After nearly a year of war with the Palestinian Islamist movement Hamas in Gaza, Israel shifted its focus to Lebanon in late September, vowing to secure its northern border threatened by cross-border fire from Hamas's Lebanese ally.
Israel ramped up its air strikes on Hezbollah strongholds around the country and sent in ground troops late last month, in a war that has killed at least 1,552 people since September 23, according to an AFP tally of Lebanese health ministry figures.
Fighting meanwhile raged in Lebanon, with the Israeli military again striking the southern suburbs of Beirut Tuesday evening, after issuing new calls for residents to evacuate the area.
On Tuesday, an Israeli strike on the eastern Hermel region killed five people, while five more died from a separate strike in the southern city of Nabatiyeh, the Lebanese health ministry said.
An Israeli air strike near a Beirut hospital killed 18 people, four of them children, according to the ministry.
The strike flattened four buildings near the Rafic Hariri Hospital, Lebanon's biggest public health facility which is outside Hezbollah's traditional strongholds, an AFP correspondent reported.
Resident Ola Eid said she was tossing children chocolate and candy from her balcony when her neighbourhood was bombed.
"Before they could even catch them, the first strike hit, then a second. I saw the children ripped apart," she told AFP.
UN human rights chief Volker Turk said he was "appalled" by the strike.
Hezbollah also continued to fire into Israel through Tuesday, launching about 140 "projectiles" from Lebanon, the Israeli military said.
