Israel launched a series of intense airstrikes in southern Lebanon early Sunday, in what it said was a preemptive attack against the Hezbollah militant group.

Soon afterwards, Hezbollah announced it had launched an attack on Israel with a "large number of drones" as an initial response to last month's assassination of Fuad Shukr, a top commander with the group, in a strike in Beirut's southern suburbs last month.

Hezbollah later said it had completed the "first phase" of its response the killing, adding it hit 11 Israeli military sites, fired more than 320 rockets and sent drones flying into northern Israel.

Israeli Prime Minister Benjamin Netanyahu's office said he and his defence minister, Yoav Gallant, were managing the latest operation from military headquarters in Tel Aviv.

Gallant declared a "special situation on the home front," and Netanyahu's Security Cabinet was set to meet later Sunday morning. 

Air raid sirens were reported throughout northern Israel, and Israel's Ben-Gurion international airport diverted incoming flights and delayed takeoffs, but the airport is expected to begin resuming flights. 

There were no immediate reports of any casualties from the cross-border rocket fire and airstrikes.

Hezbollah began attacking Israel almost immediately after the war with Hamas erupted on Oct. 7 with a Hamas cross-border attack.

The latest attack came as Egypt hosts a new round of talks aimed at ending Israel's war against Hamas, now in its 11th month.

Hezbollah has said it will halt the fighting if there is a ceasefire.

Last week, Israel's defence minister said he was moving more troops toward the Lebanese border in anticipation of possible fighting with the Iranian-backed group.

Israel and Hezbollah have been exchanging fire nearly daily, displacing tens of thousands of people on both sides of the border and raising fears that the fighting could escalate into all-out war.

But until Sunday, both sides have been careful to avoid a broader conflagration.

Hezbollah is considered much more powerful than its ally, Hamas, with an estimated arsenal of 150,000 rockets and missiles, including precision-guided missiles.

In recent months the group has also stepped up its use of drones, against which Israel is less well-equipped to defend.