The Israeli military has said they killed Hassan Nasrallah, the leader of the Hezbollah militant political group, in an air strike in Beirut on Friday.

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

Mr Nasrallah has lead Hezbollah for more than three decades.

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

Smoke rises as a building collapses in Beirut’s southern suburbs (Hussein Malla/AP)

Hours before the strikes, Israeli Prime Minister Benjamin Netanyahu addressed the United Nations, vowing that his country’s campaign against Hezbollah would continue — further dimming hopes for an internationally backed cease-fire.

Mr Netanyahu abruptly cut his United States visit short and returned to Israel.

Mr Nasrallah has been in hiding for years, rarely appearing in public. He regularly gives speeches, but always by video from unknown locations.

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.