THE mass bombing attack in Lebanon on Hezbollah’s communication devices was a “severe blow” and Israel crossed a “red line,” the leader of the group said today.

Hassan Nasrallah added that the terrorist attack was a “declaration of war.”

He made the comments in a televised speech from an unknown location as Hezbollah and the Israeli military traded new strikes over the border.

Israeli war planes broke the sound barrier as it flew low over Beirut, sending people fleeing in panic and offices rushing to open windows to avoid glass shattering.

At least 37 people were killed, including a nine-year-old girl and another child, and some 3,000 others were wounded in the two blasts this week as pagers and walkie-talkie devices exploded in actions planned over months, which involved the infiltration of civilian European supply chains.

Lebanese Prime Minister Najib Mikati called on the United Nations today to “take a firm stance” against Israel after multiple reports said that its spy agency Mossad was behind the attacks.

Israel has not openly claimed responsibility for the device blasts, but leaders have warned that they could launch a stepped-up military operation against Lebanon.

Mr Nasrallah said that the group is investigating how the bombings were carried out.

“Yes, we were subjected to a huge and severe blow,” he said.

“The enemy crossed all boundaries and red lines.”

He vowed that Hezbollah will keep up its attacks along Lebanon’s border with Israel as long as the latter’s war on Gaza continues.

“The Lebanese front will not stop before the aggression on Gaza stops,” Mr Nasrallah said.

He said that the attacks will be met with a response “in a way that they might expect and that they might not.”

“You will find out when it happens,” he said.

“This reckoning will happen. The details, we won’t reveal now, because we are now in a very sensitive stage of the battle.”

Israeli Defence Minister Yoav Gallant told troops yesterday that they are “at the start of a new phase in the war.”

Without mentioning the exploding devices, he praised the work of the Israeli army and security agencies, saying “the results are very impressive.”

The attacks on Tuesday and yesterday have left people in Lebanon fearing a full-scale war.

One woman told the BBC: “A state of panic overwhelmed people to the point that they have become afraid to walk next to each other and frankly, this situation is very frightening.”