Lebanon's Iran-backed Hezbollah group on Saturday confirmed its leader Hassan Nasrallah had been killed, after Israel said it had "eliminated" him in a strike on south Beirut 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.

The statement confirmed he was killed with other group members "following the treacherous Zionist strike on the southern suburbs" of Beirut.

In central Beirut women were seen weeping in the streets right after Hezbollah announced the news.

Israeli jets pounded Beirut's south and its outskirts throughout the night into Saturday in the most intense attacks on the Hezbollah stronghold since the group and Israel last went to war in 2006. (AFP)