The Lebanese group has not confirmed his death.
In a statement, the Israeli army said that alongside Nasrallah, the commander of Hezbollah’s Southern Front, Ali Karaki, was also killed, along with other commanders.
"Hassan Nasrallah is dead," Israeli military Spokesman Nadav Shoshani announced on X.
Meanwhile, a source close to the Lebanese group told AFP on condition of anonymity that contact with Nasrallah had been lost since Friday evening.
He did not confirm whether Nasrallah had been killed.
The source said that during Israel's last war with Hezbollah, in 2006, contact had been lost for two days with the group leader, sparking rumours that he had been killed. The rumours were later dispelled after Nasrallah emerged unscathed.
Shortly after the Israeli announcement, air-raid sirens rang out in Israeli settlements north of Jerusalem, warning of an exceptionally far-ranging rocket attack from Lebanon.
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