About 100,000 people have fled to shelters in Lebanon and the number of displaced is expected to rapidly increase following "unprecedented" Israeli warnings ordering people out of large parts of the country, a senior U.N. official said Friday.

With war raging between Israel and Lebanon's Hezbollah, the Israeli military on Thursday ordered residents out of Beirut's southern suburbs, including areas controlled by the Iran-backed group, as well as parts of the eastern Bekaa Valley, after ordering people out of a swathe of south Lebanon on Wednesday.

"What we saw in the last couple of days is, I would say ... unprecedented in terms of the scale here in Lebanon of the warnings, the displacement orders, and the reaction, the panic also, that this has all created," Imran Riza, U.N. humanitarian coordinator in Lebanon, told Reuters.

"At the moment, there are about 100,000 people that are, as of this morning, in some 477 collective shelters. There are some 57 shelters that still have some space, but basically the capacity is being reached very, very quickly," Riza said.

Noting the panic and gridlock caused by the Israeli displacement orders, Riza said: "We had people moving all over the place and not knowing where to go to. So yes, I think we're going to have an increased number quite quickly."

He noted that more than a million people were uprooted in Lebanon during a war between Hezbollah and Israel in 2024, 75%-80% of whom were not in shelters.

"This time again, the majority will not be in shelters probably," he said.