Israel on Friday said it struck hundreds of targets in Lebanon, hours after Hezbollah's leader vowed to retaliate for two "unprecedented" rounds of attacks targeting its operatives' communication devices.

Israel has not commented on the explosion of thousands of Hezbollah pagers and radios, which killed 37 people and wounded nearly 3,000 over two days this week, but it has been blamed by the Iran-backed group for the attacks.

Speaking for the first time since the deadly device sabotage, Hezbollah leader Hassan Nasrallah vowed on Thursday that Israel would face retribution.

Describing the attacks as a "massacre" and a possible "act of war", Nasrallah said Israel would face "tough retribution and just punishment, where it expects it and where it does not".

As he delivered his televised address, Israeli warplanes broke the sound barrier over Beirut.

Hours later, Israel's military said its jets hit "approximately 100 launchers and additional terrorist infrastructure sites, consisting of approximately 1,000 barrels" set to be fired immediately.

According to Lebanon's state-run National News Agency, Israel struck the south of Lebanon at least 52 times.

Iran-backed Hezbollah meanwhile said it launched at least 17 attacks on military sites in northern Israel.

The device blasts and Thursday's barrage of air strikes came after Israel announced it was shifting its war objectives to its northern border with Lebanon where it has been trading fire with Hezbollah.

For nearly a year, Israel's firepower has been focused on Palestinian militant group Hamas in Gaza, but its troops have also been engaged in near-daily clashes with Hezbollah militants.

International mediators have repeatedly tried to avert a full-blown war between Israel and Hezbollah and staunch the regional fallout of the war in Gaza, started by Hamas's October 7 attack on Israel.

Hezbollah maintains its fight is in support of Hamas, and Nasrallah vowed the attacks on Israel would continue as long as the war in Gaza lasts.

The cross-border exchanges of fire have killed hundreds in Lebanon, most of them fighters, and dozens in Israel, including soldiers.

Tens of thousands of people on both sides of the border have been forced to flee their homes. (AFP)