"The series of strikes launched by the Israeli enemy Thursday evening led to the death of four people," the Lebanese health ministry said.

The Israeli military said Thursday that it had targeted Hezbollah "infrastructure that was used for producing and storing strategic weapons" in south Lebanon and the eastern Bekaa Valley.

Israeli Defence Minister Israel Katz described one of the targets as Hezbollah's "biggest precision missile manufacturing site".

More than a year of hostilities -- including two months of all-out war between Israel and Hezbollah which largely ended with a November ceasefire -- left the militant group badly weakened.

Israel has nonetheless kept up near-daily air strikes in Lebanon despite the ceasefire, and has threatened to continue them until the group has been disarmed.

"Any attempt by the terrorist organisation to recover, re-establish or threaten will be met with relentless intensity," Katz said on Thursday.

Under the terms of the truce, Hezbollah was to withdraw its fighters north of the Litani river, about 30 kilometres (20 miles) from the Israeli border.

Israel was meant to withdraw all its troops from Lebanon, but has kept them in five areas it deems strategic.

In a speech on Thursday, Lebanese President Joseph Aoun said he was determined to disarm Hezbollah, a step he has come under heavy US pressure to take, despite the group's protests that doing so would serve Israeli goals.