Israel said its air force attacked Hezbollah's intelligence headquarters in Beirut on Sunday as well as an underground workshop for the production of weapons.
In a statement, the Israeli military said its fighter jets killed three Hezbollah commanders, including Alhaj Abbas Salameh, a senior figure in the group's southern command, Radja Abbas Awache, a communications expert, and Ahmad Ali Hussein, who it said was responsible for strategic weapons development.
It was not clear if the three were killed in the attack on the headquarters or in separate actions.
Hezbollah made no immediate comment.
Israel's military said on Saturday it had destroyed tunnel shafts and underground infrastructure in southern Lebanon and killed Hezbollah's deputy commander of the Bint Jbeil area on Friday.
Early on Sunday, two Israeli strikes targeted the Harat Hreik neighborhood in the southern suburbs of Beirut, hitting a residential building near Bahman Hospital, Lebanon's state-run national news agency said.
Reuters witnesses saw smoke rising from Beirut's suburbs on Sunday morning, but it was not clear if this was a result of the same strike.
Meanwhile, Hezbollah said it launched rockets on Sunday at an Israeli army base east of the northern town of Safed, adding the attack was "in defence of Lebanon" and "in response to the Israeli enemy's attacks on villages and homes".
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