Kenya's President William Ruto (L) and Antonio Guterres arrive to attend the 2024 United Nations Civil Society Conference in Nairobi on Friday. AFP

Earlier this week, Israeli ground troops seized eastern areas of the city, including the Palestinian side of the Rafah border crossing between Egypt and Gaza, but they have yet to enter its main built-up area.

AFP journalists witnessed artillery strikes on the city on Friday and the Israeli army said operations were continuing in the east of the city.

"On the Gazan side of the Rafah crossing, the troops eliminated several terror cells during close-quarters combat and with an aerial strike," the military said.

But there was no sign yet of the full-scale assault promised by Prime Minister Benjamin Netanyahu even after US President Joe Biden threatened on Wednesday to halt some arms deliveries if he goes ahead.

"If we have to stand alone, we will stand alone," the Israeli premier said in a statement late on Thursday. "We are determined and we are united in order to defeat our enemies and those who want to destroy us."

Aid operations 'crippled'

Israel's military operations around Rafah have already had a severe impact on Gaza civilians, UN agencies said.

The Rafah crossing, which Israeli troops closed on Tuesday, is the only one equipped to handle deliveries of fuel and the United Nations says stocks inside Gaza have now run out, effectively halting all humanitarian operations.

"In Gaza there are no stocks (of fuel)... (That) means no movement," said Andrea De Domenico, who heads the UN humanitarian office in the Palestinian territories. "It is completely crippling the humanitarian operations."

More than 100,000 people, many of them already displaced from other areas of Gaza, have fled Rafah this week, the UN said.

Most have taken to the road with only what they can carry and little idea of where they might find shelter, let alone safety.

Many have returned to the city of Khan Yunis, where intense fighting raged earlier this year, or are crowded into shelters along the seashore in the central town of Deir Al Balah.

UNWRA chief Philippe Lazzarini said the agency had been forced to act after twin arson attacks by "Israeli extremists" on the compound's perimeter put the lives of staff at "serious risk".

He described how "a crowd accompanied by armed men were witnessed outside the compound chanting 'Burn down the United Nations'." EU foreign policy chief Josep Borrell said the bloc "strongly condemns the attack."

"It is Israel's responsibility to ensure the safety of humanitarian workers. UNRWA is an irreplaceable lifeline to millions in Gaza and the region," he said in a post on X.

UN chief Guterres echoed his comments. "Targeting aid workers and humanitarian assets is unacceptable, and must stop," he said in a post.

  Agence France-Presse