At least 100,000 people have crossed from Lebanon into Syria fleeing Israel’s bombardment, the UN refugee agency’s chief said.

“The number of people who have crossed into Syria from Lebanon fleeing Israeli airstrikes – Lebanese and Syrian nationals – has reached 100,000. The outflow continues,” UNHCR’s chief Filippo Grandi said in a post on X on Monday.

The UN agency is operating at four crossing points along with local authorities and the Syrian Red Crescent, Grandi noted.

There are at least 1.5 million Syrian refugees who live in Lebanon, government figures cited by UNHCR show.

Many of them fled the war in Syria that started in 2011 when an initially peaceful antigovernment uprising was met with a brutal crackdown by President Bashar al-Assad.

However, the flow has started to reverse in recent days as the Israeli military has stepped up its operations against Iran-backed armed group Hezbollah, pounding Lebanon with air raids that have killed more than 700 in the last week.

The dramatic escalation comes as Israel has shifted its focus from fighting Hamas in Gaza to its northern frontier, where it has traded nearly daily crossfire with Hezbollah since the start of the war in Gaza in October.

Israel’s stated aim in its offensive in Lebanon is to allow the return of tens of thousands of Israeli civilians to their homes in the north of Israel.

However, its operations against Hezbollah, including the detonation of electronic communications devices that killed 39 and injured thousands, and its subsequent killing of Nasrallah, appear to have raised confidence that it could destroy its longstanding enemy in Lebanon.

The bombardment has seen the stream of people escaping into Syria grow rapidly. On Friday it was reported that 30,000 had crossed the border.

There are now growing signs that a ground offensive could be launched, which would displace a higher number of people.

Lebanon’s caretaker Prime Minister Najib Mikati said recently that Israeli air raids may have already forced a million people to leave their homes in the worst displacement in the country’s history.

The International Organization for Migration has mapped 200,000 of those displaced.