BEIRUT/JERUSALEM (Reuters) -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.
Israel's military said on Thursday it had struck hundreds of Hezbollah rocket launchers that had been set to fire towards Israel, in what security sources in Lebanon said was the heaviest such attack since hostilities began last October.
Ignited by the Gaza war, the conflict has intensified significantly this week, with Hezbollah suffering an unprecedented attack in which pagers and walkie talkies used by its members exploded, killing 37 people and wounding thousands.
The batteries of the walkie-talkies were laced with a highly explosive compound known as PETN, a Lebanese source familiar with the device's components told Reuters.
The way the explosive material was integrated into the battery pack made it extremely difficult to detect, the source said.
The UNIFIL peacekeeping force in south Lebanon said on Friday morning that the previous 12 hours had seen "a heavy intensification of the hostilities" across the Lebanese-Israeli border and in its area of operations.
"We are concerned at the increased escalation across the Blue Line and urge all actors to immediately de-escalate", UNIFIL spokesperson Andrea Tenenti told Reuters, referring to the line that delineates the border between Lebanon and Israel.
Israeli airstrikes on Friday hit at least three villages in south Lebanon, according to security sources in Lebanon and Hezbollah's al-Manar television, which broadcast footage of a cloud of smoke rising from one of the attacks.
There was no immediate comment from the Israeli military.
Hezbollah said its fighters had fired a guided missile at Israeli troops in Metula, an Israeli town on the border targeted frequently by the Lebanese group over the last year.
Israeli radio reported that residents of several towns in northern Israel were instructed by the military's Homefront Command to stay close to their shelters.
The military had earlier lifted orders restricting movement and large gatherings that it had issued on Thursday night for a number of communities in the north and the Golan Heights. The restrictions were ordered following the start of the strikes.
Security sources in Lebanon said four people were wounded in Israel's intensive bombardment on Thursday. It was not immediately clear if they were Hezbollah members.
The year-long conflict between Israel and Hezbollah is the worst since they fought a war in 2006. Tens of thousands have had to leave homes on both sides of the border.
While the conflict has largely played out in areas at or near the frontier, this week's escalation has heightened concerns that it could widen and further intensify.
The United States on Thursday warned all parties in the Middle East against escalation, saying Washington's priority is to find a diplomatic solution.
"We will continue to stand by Israel's right to defend itself, but we don't want to see any party escalate this conflict, period," State Department spokesperson Matthew Miller told a news briefing.
More than 460 Hezbollah fighters have been killed since the most recent hostilities with Israel broke out almost a year ago, in addition to some 170 civilians, according to sources in Lebanon.
In Israel, at least 52 people have been killed - half of them civilians and half of them soldiers - according to the Israeli Institute for National Security Studies.
SECURITY COUNCIL TO MEET
The 15-member United Nations Security Council is due to meet on Friday over the blasts.
In a TV address on Thursday, Hezbollah leader Sayyed Hassan Nasrallah said the device explosions on Tuesday and Wednesday "crossed all red lines" and vowed to punish Israel.
Israel has not directly commented on the pager and radio detonations, which security sources say were probably carried out by its Mossad spy agency.
Israeli Defence Minister Yoav Gallant said late on Thursday that Israel will keep up military action against Hezbollah.
Israel has said its goal is to ensure the safe return of Israelis to northern Israel.
Hezbollah, an ally of the Palestinian militant group Hamas, says its attacks on northern Israel aim to support Palestinians under Israeli fire in the Gaza Strip.
Nasrallah said on Thursday that the Lebanese front would not stop "before the halt of the aggression on Gaza".