A preliminary investigation by Lebanese authorities into the communications devices that blew up in Lebanon this week found that they were implanted with explosives before arriving in the country, according to a letter sent to the U.

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.

Walkie-talkies and solar equipment exploded in Beirut and multiple parts of Lebanon on Wednesday in an apparent second wave of attacks.

The United Nations Security Council will meet on Friday over the pager blasts in Lebanon targeting militant group Hezbollah, said Slovenia's U.N. Ambassador Samuel Zbogar, president of the 15-member council for September.

Explosions in Lebanon appear to be a pre-emptive strike before a major military operation, argues the UN chief. The United Nations High Commissioner for Human Rights, Volker Turk, calls for an independent investigation.