Israel's military carried out airstrikes in Rafah on Monday, residents said, hours after Israel told Palestinians to evacuate parts of the southern Gaza city where more than a million people uprooted by the war have been sheltering.

Fears are growing of a full-blown assault in Rafah, long threatened by Israel, against holdouts of the Palestinian militant group Hamas as ceasefire talks in Cairo stall.

There was no immediate comment from Israel, which Hamas-affiliated Al-Aqsa TV said had targeted areas in eastern Rafah near neighbourhoods given evacuation orders.

Instructed by Arabic text messages, phone calls, and flyers to move to what the Israeli military called an "expanded humanitarian zone" 20 km (7 miles) away, some Palestinian families began trundling away under chilly spring rain.

Some piled children and possessions onto donkey carts, while others left by pick-up or on foot through muddy streets.

"It has been raining heavily and we don't know where to go. I have been worried that this day may come, I have now to see where I can take my family," one refugee, Abu Raed, told Reuters via a chat app.

A senior Hamas official said the evacuation order was a "dangerous escalation" that would have consequences. "The U.S. administration, alongside the occupation, bears responsibility for this terrorism," the official, Sami Abu Zuhri, told Reuters, referring to Israel's alliance with Washington.

Hamas said later in a statement that any offensive in Rafah would not be a "picnic" for Israeli forces and said it was fully prepared to defend Palestinians there.

Aid agencies have warned that the evacuation order will lead to an even worse humanitarian disaster in the crowded coastal enclave of 2.3 million people reeling from seven months of war.

"Forcing over a million displaced Palestinians from Rafah to evacuate without a safe destination is not only unlawful but would lead to catastrophic consequences," British charity ActionAid said.

Israel's military said it had urged residents of Rafah to evacuate in a "limited scope" operation. It gave no specific reasons nor did it say if offensive action might follow.

Nick Maynard, a British surgeon trying to leave Gaza on Monday, said in a voice message from the Gaza side of the Rafah crossing into Egypt: "Two huge bombs have just gone off immediately outside the crossing. There’s a lot of gunfire as well about 100 meters from us. We are very unclear whether we will get out."

"Driving through Rafah, the tension was palpable with people evacuating as rapidly as they could."

'BIGGEST CATASTROPHE'

Witnesses said the areas in and around Rafah where Israel wants to move people are already crowded with little room for more tents. "The biggest genocide, the biggest catastrophe will take place in Rafah. I call on the whole Arab world to interfere for a ceasefire - let them interfere and save us from what we are in," said Aminah Adwan, a displaced Palestinian.

Israel has been threatening to launch incursions in Rafah, which it says harbours thousands of Hamas fighters and potentially dozens of hostages.

Victory is impossible without taking Rafah, it says.

The prospect of a high-casualty operation worries Western powers and neighbouring Egypt, which is trying to mediate a new round of truce talks between Israel and Hamas under which the Palestinian Islamist group might free some hostages.

But an unnamed "high-level" source was quoted by Egypt's state-affiliated Al Qahera news TV as saying on Monday that talks had hit an impasse since Hamas launched an attack in the vicinity of the Kerem Shalom crossing into Gaza on Sunday, killing four Israeli soldiers.

Egypt raised its military level of preparedness in northern Sinai, which borders Gaza, security sources said on Monday.

The European Union, France and Jordan reiterated their opposition to any offensive in Rafah.

The Rafah plan has opened an unusually public rift between Israel and Washington, which has repeatedly warned its ally not to attack the city because of potential civilian casualties.

An Israeli broadcaster, Army Radio, said the evacuations were focused on a few peripheral districts of Rafah, from which people would be directed to tent cities in nearby Khan Younis and Al Muwassi.

In an overnight aerial attack on Rafah, Israeli planes hit 10 houses, killing 20 people and wounding several, medical officials said. The Israeli military said it had attacked the site of Sunday's mortar launch that killed the four Israeli soldiers as well as a group of gunmen.

"Our just war in Gaza continues with the exact same goals: the release of all hostages and the defeat of Hamas," Israeli Foreign Minister Israel Katz said on Monday on X.

The war began after Hamas stunned Israel with a cross-border raid on Oct. 7 in which 1,200 people were killed and 252 hostages taken, according to Israeli tallies.

More than 34,700 Palestinians have been killed and more than 78,000 have been wounded in Israel's assault, according to Gaza's health ministry.

The United Nations has accused Israel of denying aid to Gazans, with World Food Programme head Cindy McCain saying in a weekend interview that there was already "full-blown famine" in the north of the territory.