Armoured personnel carriers and bulldozers were also seen as Israel expanded its operations against Hamas in response to the Palestinian militant group's deadly October 7 attack on southern Israel.

Amin Abu Hawli, 59, said the Israeli vehicles were "two kilometres (1.2 miles) inside" the Palestinian territory in the village of Al-Qarara near Khan Yunis.

Moaz Mohammed, 34, said Israeli tanks were on the southern part of Salah al-Din road which runs from the north to the south of the strip.

"They are holding Salah al-Din road on both sides and are now cutting it between Deir al-Balah (in central Gaza) and Khan Yunis, firing bullets and tank shells at cars and people trying to move through the area," he said.

Since a truce expired on Friday, fighting in Gaza has resumed, as have militants' rocket launches toward Israel and Israel's air strikes on the Palestinian territory.

In its latest estimate, the UN humanitarian agency OCHA said around 1.8 million people in Gaza, roughly 75 percent of the population, had been displaced, many to overcrowded and unsanitary shelters.

Many people have been forced to flee to the south of the Gaza Strip and fear being pushed towards the border with Egypt.

Israeli military spokesman Jonathan Conricus said on Monday that Israel was not "trying to displace anyone".

"We are not trying to move anybody from anywhere permanently," he said.

Many Palestinians fear a repeat of the displacement of 760,000 Palestinians that took place during the war that led to Israel's creation 75 years ago.