Deadly Israeli attacks that blew up Hezbollah radios and pagers crossed all red lines, the leader of the heavily armed Lebanese movement said on Thursday, in a speech broadcast as sonic booms from Israeli warplanes shook buildings in Beirut.

Lebanon and Hezbollah have blamed Israel for attacks on Hezbollah's communications equipment that killed 37 people and wounded around 3,000, overwhelming Lebanese hospitals and wreaking bloody havoc on Hezbollah. Although Israel has neither confirmed nor denied its involvement, it's widely believed that intelligence officials from the country were responsible for the attacks.

"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," Hezbollah leader Hassan 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 or war, they could be called anything and they deserve to be called anything. Of course that was the intention of the enemy."

WATCH | How were devices used by Hezbollah made to explode?: 

How did attackers turn Hezbollah's devices into bombs?

After a second wave of deadly explosions in Lebanon, experts are now analyzing how attackers were able to penetrate Hezbollah’s security to rig thousands of pagers and other devices with explosives.

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 airstrikes 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.

Attacks 'big, harsh blow,' Nasrallah says

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 5,000 people, he also played down the impact 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.

The attacks on Hezbollah communications equipment sowed fear across Lebanon, with people abandoning electronic devices for fear of carrying bombs in their pockets.

"Who can even secure their phone now? When I heard about what happened yesterday, I left my phone on my motorcycle and walked away," said Mustafa Sibal on a street in Beirut.

Citizens asked to report any suspicious devices

The Lebanese army said on Thursday it was blowing up pagers and suspicious telecom devices in controlled blasts in different areas. It called on citizens to report any suspicious devices.

Lebanese authorities banned walkie-talkies and pagers from being taken on flights from Beirut airport until further notice, the National News Agency reported. Such devices were also banned from being shipped by air.

Hezbollah fired missiles at Israel on the day after the Oct. 7 cross-border attack by the Palestinian militant group Hamas, which triggered the Gaza war, and since then, constant exchanges of fire have occurred. Although neither side has allowed this to escalate into a full-scale war, it has led to the evacuation of tens of thousands of people from the border area on both sides.

"The Hezbollah terrorist organization has turned southern Lebanon into a combat zone. For decades, Hezbollah has weaponized civilian homes, dug tunnels beneath them, and used civilians as human shields," Israel's military said.

"The IDF [Israel Defence Forces] is operating to bring security to northern Israel in order to enable the return of residents to their homes, as well as to achieve all of the war goals."

Israel said its warplanes struck villages in southern Lebanon overnight, and a security source and Hezbollah's al-Manar TV reported airstrikes near the border began again on Thursday just after midday.

Thousands wounded, nearly 40 dead

Hand-held radios used by Hezbollah detonated on Wednesday across Lebanon's south, killing 25 people and wounding hundreds.

The previous day, hundreds of pagers — used by Hezbollah to evade mobile phone surveillance — exploded at once, killing 12 people including at least two children, and injuring more than 2,300.

Lebanese Prime Minister Najib Mikati called on the United Nations Security Council to take a firm stand to stop what he called Israel's "aggression" and "technological war" against his country.

Israel says its conflict with Hezbollah, like its war in Gaza against Hamas, is part of a wider regional confrontation with Iran, which sponsors both groups as well as armed movements in Syria, Yemen and Iraq.

Also on Thursday, Israeli security forces said that an Israeli businessman had been arrested last month after attending at least two meetings in Iran where he discussed assassinating Prime Minister Benjamin Netanyahu, the defence minister or the head of the Shin Bet spy agency.

Last week, Shin Bet uncovered what it said was a plot by Hezbollah to assassinate former Defence Minister Moshe Ya'alon.

Israel has been accused of assassinations, including a blast in Tehran that killed the leader of Hamas and another in a Beirut suburb that killed a senior Hezbollah commander within hours of each other in July.

Despite the events of the past few days, a spokesperson for the UN peacekeeping mission in southern Lebanon said the situation along the frontier had "not changed much in terms of exchanges of fire between the parties.

"There was an intensification last week. This week it is more or less the same. There are still exchanges of fire. It is still worrying, still concerning, and the rhetoric is high," the spokesperson, Andrea Tenenti, said.