Tens of thousands of Lebanese have fled their homes in the face of intensifying Israeli bombardment, the United Nations has said.

Israel continued its massive air strike campaign on Tuesday after close to 500 people were killed and thousands injured by its bombs the previous day. The attacks have seen Lebanese civilians continue to seek to escape the south of the country, although strikes have also hit locations across the country.

“We are gravely concerned about the serious escalation in the attacks that we saw yesterday,” UN refugee agency spokesman Matthew Saltmarsh told reporters in Geneva on Tuesday.

“Tens of thousands of people were forced from their homes yesterday and overnight, and the numbers continue to grow,” he said.

Israeli air raids killed at least 492 people on Monday, including 35 children, according to Lebanon’s Ministry of Health, marking the deadliest bombardment of the country in nearly two decades.

Longtime foes Hezbollah and Israel have been locked in near-daily cross-border exchanges of fire since Palestinian group Hamas staged an unprecedented attack on Israel last October 7.

However, Israel has now boosted its operations. Monday’s bombardment was by far the largest it has launched against Lebanon since a full-scale war raged between Israel and the Iran-backed Hezbollah in the summer of 2006.

“This is a region that has already been devastated by war and a country that knows suffering all too well,” Saltmarsh said. “The toll on civilians is unacceptable.”

Ravina Shamdasani, spokeswoman for the UN Human Rights Office, said the agency was “extremely alarmed” by the sharp escalation of hostilities and called on “all parties to immediately cease the violence and to ensure the protection of civilians”.

UNICEF decried the impact of the attack on children.

“We are warning today that any further escalation in this conflict will be absolutely catastrophic for all children in Lebanon,” said Ettie Higgins, UNICEF’s deputy representative in Lebanon.

“Yesterday was Lebanon’s worst day in 18 years. This violence has to stop immediately, or the consequences will be unconscionable.”