An initial investigation by Lebanese authorities has found that hand-held devices that exploded this week were booby-trapped before they entered the country, Lebanon's mission to the United Nations said Thursday.

"Initial investigations showed that the targeted devices were professionally booby-trapped... before arriving in Lebanon, and were detonated by sending emails to the devices," said the letter seen by AFP, which blamed Israel for the attacks.

The blasts that killed 37 people and wounded nearly 3,000 over two days targeted communication devices used by the Iran-backed Hezbollah group.

Pagers and walkie-talkies exploded as their users were shopping in supermarkets, walking on streets and attending funerals, plunging the country into panic.

Israel has not commented on the operation but has said it will widen the scope of its war in Gaza to include the Lebanon front.

Lebanon's mission said the attack was "unprecedented in its brutality" and compromised diplomatic efforts to halt fighting in Gaza and south Lebanon.

It called on the UN Security Council to condemn the attack ahead of an emergency session planned for Friday to discuss the blasts.

Lebanese Foreign Minister Abdallah Bou Habib is expected to attend the meeting, diplomatic sources told AFP.

Iran-backed Hezbollah is an ally of Palestinian militant group Hamas, which has been fighting a war in Gaza since its October 7 attack on Israel.

For nearly a year, the focus of Israel's firepower has been on Gaza but its troops have also been engaged in near-daily clashes with Hezbollah militants along its northern border.

Hundreds have been killed in Lebanon, most of them fighters, and dozens in Israel, including soldiers.

The exchanges of fire have forced tens of thousands of people on both sides of the border to flee their homes.