Heavy explosive weapons with wide-area effects struck bustling neighbourhoods, including the capital Beirut, without effective advance warnings, the International Committee of the Red Cross said in a statement.

"People across Lebanon were holding their breath for a ceasefire agreement, but a wave of deadly strikes plunged the country into panic and chaos," said Agnes Dhur, the ICRC's head of delegation in Lebanon.

"Many who had begun thinking of the moment when they might return to their homes have been rushing to streets and hospitals, searching for missing loved ones or seeking a safety that feels increasingly out of reach."

At least 112 people were killed and 837 more were wounded on Wednesday after Israel launched a wave of strikes unprecedented in the current war, according to the latest Lebanese health ministry toll.

Across the country, the Lebanese Red Cross sent 100 ambulances to evacuate the dead and transport the wounded to hospitals, the ICRC said.

Already overwhelmed medical facilities were having to deal with the influx of casualties, while some people remained trapped under the rubble, it added.

"Any comprehensive agreement for the region must consider the safety, protection and dignity of civilians in Lebanon," the Geneva-based ICRC said.

"After more than five weeks of hostilities, people urgently need respite from the violence."

Lebanon was drawn into the Middle East war on March 2 when Tehran-backed militant group Hezbollah began firing rockets into Israel to avenge the killing of Iranian supreme leader Ayatollah Ali Khamenei.