UNICEF, the UN children's agency, called the figures "staggering" and stressed that under international humanitarian law, children had to be protected at all times during conflict.

"According to the Lebanese Ministry of Public Health, 77 children have reportedly been killed or injured over the past week alone," UNICEF spokesman Ricardo Pires told a media briefing in Geneva.

"Fifteen children killed and 62 injured in seven days. That's an average of 11 children every 24 hours.

"We understand the vast majority of these children were impacted by airstrikes in south Lebanon. Only yesterday, seven children were killed and 30 injured," he said.

A ceasefire between Israel and the Iran-backed Lebanese group Hezbollah was supposed to have taken effect on April 17 but has never been observed. Both sides accuse each other of violating it and justify their attacks by the other camp's alleged breaches.

In total, since the ceasefire was announced, 55 children have been killed and 212 wounded, Pires said.

Pires called for all parties to respect the ceasefire in full and to comply at all times with international humanitarian law, under which "children and civilian infrastructure must be protected at all times".

Lebanon was drawn into the Middle East war in early March when Hezbollah launched rockets at Israel over the killing of Iran's supreme leader in US-Israeli attacks, prompting Israeli strikes and a ground invasion.

In recent days, Israel has issued repeated evacuation warnings to swathes of the southern coastal city of Tyre and carried out heavy strikes.