Israeli tanks and jets pounded Gaza City, the target of a major ground offensive, on Thursday, prompting Palestinians to flee south, where the Israeli military announced the deaths of four soldiers.

A steady stream of Gazans headed south on foot, in vehicles and on donkey carts – their meagre belongings piled high.

"There is artillery fire, air strikes, quadcopter and drone gunfire. The bombing never stops," said Aya Ahmed, 32, sheltering with 13 relatives in Gaza City.

"The world doesn't understand what is happening. They (Israel) want us to evacuate south – but where will we live? There are no tents, no transport, no money."

Palestinians say the cost of a ride to the south has soared, in some cases topping US$1,000.

"The situation is indescribable – crowds everywhere, the sound of explosions, women and men crying and screaming as they walked while carrying their belongings," said Shadi Jawad, 47, describing his family's ordeal as they fled their home on Wednesday.

"God, send a missile to take us out and relieve us," he said.

The offensive has sparked international outrage, with the territory already devastated by nearly two years of war and the Gaza City area gripped by a UN-declared famine.

It comes ahead of a planned move by several Western countries, including France and Britain, to recognise a Palestinian state later this month at the UN.

US President Donald Trump, currently on a visit to Britain, said on Thursday he had a "disagreement" with British Prime Minister Keir Starmer over this.

"The military incursion and evacuation orders in northern Gaza are driving new waves of displacement, forcing traumatised families into an ever-shrinking area unfit for human dignity," World Health Organisation chief Tedros Adhanom Ghebreyesus said on X.

"Hospitals, already overwhelmed, are on the brink of collapse as escalating violence blocks access and prevents the WHO from delivering lifesaving supplies," he warned.

Gaza City's Al-Shifa Hospital said it had received the bodies of 33 people killed in Israeli strikes since midnight.

The Israeli military said it continued to target "Hamas terror infrastructure" and was also operating in the southern areas of Rafah and Khan Younis.

Hamas's armed wing, the Ezzedine al-Qassam Brigades, warned the military to expect fierce fighting.

"We are ready to send the lives of your soldiers to hell, and we have prepared for you an army of martyrs," the group said in a statement.

"Gaza will be a cemetery for your soldiers." (AFP)