Israel’s Prime Minister Benjamin Netanyahu says his country has “settled the score” by killing Hezbollah’s top leader with a brutal strike on Beirut.

Hassan Nasrallah, who headed the terrorist group for more than three decades, was confirmed dead by Hezbollah in the aftermath of the attack on its central command.

Netanyahu said on Sunday (AEST) that Nasrallah’s death was a “historic turning point” for the region.

He said Israel had “eliminated” a “mass murderer” who was “not just another terrorist — he was the terrorist” responsible for the deaths of thousands of people.

“Citizens of Israel, these are important days. We are in what seems to be an historic turning point,” said Netanyahu.

“Israel has momentum. We are winning.”

Hezbollah confirmed Nasrallah had been killed, without saying how.

A statement said he “has joined his fellow martyrs”.

US President Joe Biden said Nasrallah’s death was a “measure of justice for his many victims”. Biden said he was responsible for the deaths of thousands of Americans, Israelis and Lebanese.

Hezbollah said in a statement that it would continue its battle against Israel “in support of Gaza and Palestine, and in defence of Lebanon and its steadfast and honourable people”.

Hezbollah’s al-Manar TV aired Koran verses after his death was announced.

Bursts of gunfire were heard in Beirut.

Israel’s air strike — a succession of massively powerful blasts that left a crater at least 20 metres deep — shook Beirut.

Israel carried out further air strikes on the area and more widely in Lebanon on Saturday.

The Israeli military said earlier that Nasrallah was eliminated in a “targeted strike” on the group’s underground headquarters beneath a residential building in Dahiyeh — a Hezbollah-controlled southern suburb of Beirut.

It said he was killed along with another top Hezbollah leader, Ali Karaki, and other commanders.

“The strike was conducted while Hezbollah’s senior chain of command were operating from the headquarters and advancing terrorist activities against the citizens of the State of Israel,” it said.

Nasrallah’s death is by far the most significant blow in a devastating fortnight for Hezbollah, starting with a deadly attack on thousands of wireless communications devices used by its members.

Israel also significantly ramped up air strikes in Lebanon, killing several top Hezbollah commanders and hundreds of other people across wide areas of the country.

Hezbollah gave no immediate indication of who might succeed Nasrallah.

Senior Hezbollah official Sayyed Hashem Safieddine has long been regarded as heir apparent.

The group has not issued any statement on Safieddine’s status or that of any other Hezbollah leaders — apart from Nasrallah — since the attack.

Friday’s attacks on Dahiyeh were followed by more strikes on the area and other areas of Lebanon on Saturday.

Hezbollah continued its cross-border rocket fire on Saturday, setting off sirens and sending residents running for shelter deep inside Israel.

Israeli missile defences blocked some of them and there was no immediate report of injuries.

The escalation has increased fears the conflict could spin out of control, potentially drawing in Iran, Hezbollah’s principal backer, as well as the United States.

Israel says it has been attacking Hezbollah with the aim of allowing tens of thousands of residents who fled northern Israel to return home.

In Lebanon, more than 200,000 people have been displaced, about half of them since Monday.

-with AP