Pope Francis on Wednesday slammed the "terrible escalation" of the conflict in Lebanon as "unacceptable", after Israeli bombings in the south of the country targeting Hezbollah killed hundreds of people.

"I am saddened by the news coming out of Lebanon... but I hope that the international community will make every effort to stop this terrible escalation. This is unacceptable, I express my closeness to the Lebanese people, who have already suffered too much in the recent past," Francis said.

Lebanon said 51 people were killed and more than 220 injured in Israeli strikes Wednesday, including two rare strikes in mountain areas outside Hezbollah's traditional strongholds in the south and east.

An Israeli strike on the village of Joun in the Chouf mountains, southeast of Beirut, killed at least four people.

Hezbollah launched dozens of rockets into Israel on Wednesday, including a longer-range projectile that set off air raid sirens in Tel Aviv and across central Israel. It was the group’s farthest strike yet in nearly a year of exchanges.

The Israeli military said it intercepted the surface-to-surface missile, which set off air raid sirens in Tel Aviv and across central Israel, and there were no reports of casualties or damage. The military said it struck the site in southern Lebanon from which the missile was launched.

Prime Minister Benjamin Netanyahu vowed Tuesday that the Israeli military would press on with its aerial bombing campaign against Hezbollah, as Israeli jets pounded Lebanon.

"We will continue to hit Hezbollah... the one who has a missile in his living room and a rocket in his home will not have a home," Netanyahu said in a statement after visiting an Israeli intelligence base.

U.S. President Joe Biden on Tuesday urged a diplomatic solution as Israel strikes Hezbollah targets, warning against a "full-scale war" in Lebanon.

"Full-scale war is not in anyone's interest. Even though the situation has escalated, a diplomatic solution is still possible," Biden said in an address to the UN General Assembly.

Lebanon on Tuesday extended the closure of schools, universities and nurseries until the end of the week as Israeli strikes continued on east and south Lebanon and Beirut's southern suburbs.

"The closure of public and private schools" including high schools, as well as vocational institutes and universities, "is extended until the end of this week", Education Minister Abbas Halabi said in a statement. The health ministry also announced the closures of nurseries across the country until the end of the week.

Hezbollah urged Lebanese to discard Israel leaflets dropped over the country's east on Tuesday, warning against scanning barcodes that it said could compromise personal data.

"The Zionist enemy is dropping leaflets with barcodes in the Bekaa region and may drop them elsewhere," the Iran-backed group said in a statement.

Caretaker Minister of Foreign Affairs and Emigrants Abdallah Bou Habib has participated in the opening session of the 79th session of the United Nations General Assembly in New York, in the presence of U..N Secretary-General Antonio Guterres, and a large number of world leaders, kings and heads of state.

United Nations Secretary-General Antonio Guterres warned world leaders gathering in New York that Lebanon was on the "brink," a day after 558 people were killed by Israeli strikes there.

"We should all be alarmed by the escalation. Lebanon is at the brink," Guterres said at the opening of the UN's signature annual event.

World leaders on Tuesday sounded the alarm over fears of a wider war after Lebanon suffered its deadliest day in two decades due to Israeli air strikes on Hezbollah strongholds.

After nearly a year of cross-border fire since the Gaza war erupted, Israeli bombardment on Monday killed 558 people in Lebanon, including 50 children, according to the country’s health ministry.