Bombs were dropped on the south a day after Hezbollah walkie-talkies were detonated and two days after pagers held by group members blew up, with a total of 37 killed and 3,000 wounded.

Separately, sonic booms from Israeli fighter jets shook buildings in the capital Beirut in what was reportedly a mock attack while the strikes were taking place.

The jets could be heard breaking the sound barrier as Hezbollah leader Hassan Nasrallah gave a speech accusing Israel of attacks that were “unprecedented in the world”.

Nasrallah said the exploding communication devices had “crossed all red lines” and were “war crimes or a declaration of war”, and he vowed Hezbollah would respond.

Soon after, Israel announced it had launched fresh strikes on Hezbollah targets in Lebanon, according to the BBC.

Lebanon and Hezbollah have blamed Israel for both waves of device explosions that overwhelmed Lebanese hospitals and wreaked bloody havoc on the militant group.

Israel has not directly commented on the attacks, which security sources say were probably carried out by its Mossad spy agency, which has a long history of carrying out sophisticated attacks on foreign soil.

“There is no doubt that we have been subjected to a major security and military blow that is unprecedented in the history of the resistance and unprecedented in the history of Lebanon,” Nasrallah said in his TV address, filmed at an undisclosed location.

“This type of killing, targeting and crime may be unprecedented in the world,” he said, appearing in front of a featureless red background in his customary black turban.

The attacks “crossed all red lines,” he said.

“The enemy went beyond all controls, laws and morals,” he said adding the attacks “could be considered war crimes or a declaration of war, they could be called anything and they deserve to be called anything. Of course that was the intention of the enemy.”

As the broadcast was aired, deafening sonic booms from Israeli warplanes shook Beirut, a sound that has become common in recent months but has taken on a greater significance as the threat of all-out war has steadily ramped up.

Israel said its warplanes struck southern Lebanon overnight.

Hezbollah reported that air strikes resumed in the border area in the afternoon.

Nasrallah said Hezbollah hoped Israeli troops would enter southern Lebanon because that would create a “historic opportunity” for the Iran-backed group.

No military escalation, killing, assassinations or all-out war would return Israeli residents to the border area, he added, referring to a top war priority for the Israeli government.

While Nasrallah described the attacks as unprecedented, accusing Israel of trying to kill 5000 people, he also played down the effect on Hezbollah, saying the group’s structure had not been shaken.

“Yes, we received a big and harsh blow but this is also the nature of war,” Nasrallah said.

“We know that our enemy has superiority on the technological level and we have never said otherwise.”

Israel will face “a crushing response from the axis of resistance”, Iran’s Revolutionary Guards Commander Hossein Salami told Nasrallah on Thursday according to state media.

Two Israeli soldiers were killed in combat on Thursday in Israel’s north, the Israeli military said.

Israel’s N12 News said one of them was killed by a drone and the other by an anti-tank missile fired by Hezbollah across the Lebanese border.

– AAP