THE leader of militant group Hezbollah, Hassan Nasrallah, has been killed in an Israeli air strike in Beirut, it has been confirmed.

The Israeli military said the strike was carried out on Friday while the Hezbollah leadership was meeting at their headquarters in Dahiyeh.

A statement from Hezbollah on Saturday said Nasrallah “has joined his fellow martyrs”, adding that the militant group would “continue the holy war against the enemy and in support of Palestine”.

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Nasrallah has lead Hezbollah for more than three decades. He has been in hiding for years, rarely appearing in public.

Further strikes were carried out in Bekaa Valley in eastern Lebanon.

The attack levelled multiple high-rise apartment buildings, injuring 91 people and killing at least six, according to Lebanon’s health ministry.

Israeli army spokesman Rear Admiral Daniel Hagar claimed Hezbollah’s headquarters were located underground beneath the residential buildings.

Footage showed rescue workers clambering over large slabs of concrete, surrounded by high piles of twisted metal and wreckage. Several craters were visible, one with a car toppled into it. A stream of residents carrying their belongings were seen fleeing along a main road out of the district.

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The attack has sparked fears of the conflict escalating into an all-out war, dashing hopes of a ceasefire.

Iran, which has publicly backed Hezbollah for many years, said its forces "support and stand alongside" the militant group.

Hours before the strikes, Israeli Prime Minister Benjamin Netanyahu addressed the United Nations, vowing that his country’s campaign against Hezbollah would continue.

News of the blasts came as Netanyahu was briefing reporters after his UN address. A military aide whispered into his ear, and he quickly ended the briefing.

More than 720 people have been killed in Lebanon since the conflict escalated on Monday, according to Lebanon’s health ministry.

The United Nations says the number displaced by the conflict from southern Lebanon has more than doubled, with more than 211,000 people affected.