Hamas on Saturday condemned the killing of Hezbollah leader Sayyed Hassan Nasrallah after the Lebanon-based group confirmed his death in an Israeli strike on south Beirut a day earlier.

"We condemn in the strongest terms this barbaric Zionist aggression and targeting of residential buildings... and we consider it a cowardly terrorist act," the group said in a statement, offering "condolences, and solidarity with the brothers in Hezbollah and the Islamic Resistance in Lebanon on the martyrdom of... Nasrallah."

Hezbollah on Saturday confirmed its leader Sayyed Hassan Nasrallah had been killed, after Israel said it had "eliminated" him in a strike on Beirut's southern suburbs a day earlier.

"Sayyed Hassan Nasrallah, Secretary General of Hezbollah, has joined his great, immortal martyr comrades whom he led for about 30 years," Hezbollah said in a statement.

Israel's military announced Saturday that Hezbollah chief Sayyed Hassan Nasrallah was killed in an Israeli strike on Beirut the previous night, but there was no confirmation from the Lebanese armed group.

Israeli fighter jets bombarded the southern suburbs of Lebanon's capital Beirut overnight into Saturday, sending panicked families fleeing massive strikes of which one reportedly targeted Hezbollah chief Sayyed Hassan Nasrallah.

Israel said it was attacking Hezbollah's headquarters and weapons facilities, while U.S. and Israeli media reported that Nasrallah was the target of the first strike.

Hezbollah launched more than two dozen projectiles toward Israel Saturday morning, triggering sirens in more than 100 cities and towns across Israel and the Israeli-occupied West Bank.

The Israeli military said a surface-to-surface missile was fired from Lebanese territory and fell in an open area in central Israel. Israeli media said the missile fell in the sea.

EU foreign affairs chief Josep Borrell has voiced regret that no power, including the United States, can “stop” Israeli Prime Minister Benjamin Netanyahu, saying he appears determined to continue fighting in Lebanon and Gaza.

Israeli Prime Minister Benjamin Netanyahu has appeared to address Israel’s strike in Beirut's southern suburbs reportedly targeting Hezbollah leader Sayyed Hassan Nasrallah.

Israel conducted several rounds of air strikes on Hezbollah's main bastion in the southern suburbe of Beirut, sending huge clouds of smoke soaring above the densely populated area.

Israel’s military said it carried out a “precise strike” on Hezbollah’s central headquarters in south Beirut on Friday.

Israeli military spokesperson Daniel Hagari announced the strike in a televised address.

Caretaker Prime Minister Najib Mikati urged the international community to "stop" Israel from waging a "genocidal war" against Lebanon, following a huge Israeli strike on Beirut's southern suburbs.

"This new Israeli aggression proves that the Israeli enemy doesn't care about all the international efforts and calls for a ceasefire," Mikati, who is in New York, said in a statement issued by his office, urging the international community to stop the "genocidal war that it (Israel) is waging on Lebanon".