Iran's U.N. envoy warned the country had the "right to take all necessary measures to respond to this egregious violation."

First came two days of exploding pagers and walkie-talkies used by Hezbollah — deadly attacks pinned on Israel that also maimed civilians around Lebanon. Hezbollah’s leader vowed to retaliate , and on Friday the militant group launched dozens of rockets into northern Israel.

A day later, a similar attack struck walkie-talkies. In total, the explosions killed at least 37 people and injured more than 3,000, many of them civilians. Israel is widely believed to be behind the blasts, although it has neither confirmed nor denied responsibility.

The batteries of the walkie-talkies used by Lebanese armed group Hezbollah that blew up this week were laced with a highly explosive compound known as PETN, a Lebanese source familiar with the device's components told Reuters.

Lebanon blamed Israel for attacks on Hezbollah that killed 37 and wounded around 3,000, wreaking havoc on the militant group.

U.N. peacekeepers in Lebanon urged immediate de-escalation as hostilities rumbled on at the Lebanese-Israeli border on Friday, following Israel's most intense airstrikes in nearly a year of conflict with the Iran-backed Hezbollah.

By Laila Bassam and Maya Gebeily BEIRUT/JERUSALEM (Reuters) -Israeli warplanes carried out late on Thursday their most intense strikes on southern Lebanon in nearly a year of war, heightening the conflict between Israel and Lebanese armed group Hezbollah amid calls for restraint.