The UN humanitarian coordinator for Gaza said that 1.9 million people - 80% of the territory's population - were now displaced in the territory, adding she was "deeply concerned" by reports of new evacuation orders for Khan Younis.
The UN has estimated that up to 250,000 people are impacted by the Israeli military order for civilians to leave Al-Qarara, Bani Suhaila and other localities near the territory's second city of Khan Younis.
"Over 1 million people have been displaced once again, desperately seeking shelter and safety (and) 1.9 million people are now displaced across Gaza... I'm deeply concerned about reports of new evacuation orders issued in the area of Khan Younis," Sigrid Kaag told the UN Security Council.
"Palestinian civilians in Gaza have been plunged into an abyss of suffering. Their homes life shattered, their lives upended. The war has not merely created the most profound of humanitarian crises. It has unleashed a maelstrom of human misery," Ms Kaag added.
She said that not enough aid was reaching the territory, and that the opening of new crossings, particularly to southern Gaza, was necessary to avert a humanitarian disaster.
Ms Kaag said the Rafah crossing between Gaza and Egypt should be re-opened, and also pleaded with the international community to do more to fund relief efforts.
Patients, medics flee south Gaza hospital after evacuation orders - WHO
It comes as Gaza's European Hospital in Khan Younis is virtually empty with staff and patients fleeing the facility after the Israeli army ordered residents in the surrounding areas to evacuate, according to a World Health Official spokesperson.
Thousands of Palestinians, many of them already displaced multiple times by Israel the eight-month war, have fled parts of southern Gaza since yesterday amid Israeli bombardments.
"The hospital staff and the patients decided to already evacuate themselves," said Rik Peeperkorn, WHO Representative for the occupied Palestinian territories, adding that just three patients remained.
"We plea the European Gaza hospital will be spared, will be non-damaged," he told the UN press briefing, speaking by video link from Jerusalem.
An Israeli defence official claimed that although evacuation orders had been issued for the area in which the hospital is located, staff and patients were told they could stay.
"We didn't give them any order to evacuate. So patients and the medical teams can stay over there. It's safe for them," claimed Colonel Elad Goren of COGAT, the Israeli Defence Ministry agency that coordinates with the Palestinians, in a phone briefing with reporters.
The International Committee of the Red Cross, which had a medical team in the hospital, including surgeons, is moving its team and patients to a field hospital in Rafah-Mawasi, it said in a statement.
"As evacuations continue to affect so many people, it is critical that safe transport for those who are disabled, the elderly, and the sick is provided," it said.
The war started after the Hamas-led 7 October attack on southern Israel that resulted in the deaths of 1,195 people, mostly civilians, according to an AFP tally based on Israeli figures.
The militants also seized 251 hostages, 116 of whom remain in Gaza, including 42 the army claims are dead.
Israel's retaliatory war has killed at least 37,925 people, also mostly civilians, according to data from the health ministry in Gaza.
Israel has not specifically said there will be a military operation in southern Gaza, but so far nearly every evacuation order has heralded major battles.
Israeli bombardment of southern Gaza continues
Meanwhile, Israeli forces bombarded several areas of southern Gaza.
Eight Palestinians were killed and dozens wounded, health officials said. Israel's military said that two soldiers had been killed in battle a day earlier.
Israel's leaders have claimed they were winding down the phase of intense fighting against Hamas and would soon shift into what they described as more targeted operations.
Another 17 Palestinians were killed in Israeli tank shelling of a street in the densely populated Zeitoun neighbourhood in Gaza City in the north of the Strip, medics said.
Footage on some Palestinian social media that Reuters was not immediately able to verify showed the scene at a local market, with bread scattered on a floor stained with blood.
The Israeli army had ordered residents of several towns and villages in eastern Khan Younis to evacuate their homes yesterday, prior to tanks re-entering the area the military had left several weeks ago.
Thousands who had not heeded the call were forced to flee their homes in the dark overnight, as Israeli tanks and planes bombed Karara, Abassan and other areas that had been named in the evacuation orders, residents and Palestinian media said.
"Where will we go?" said Tamer, a 55-year-old businessman, who has been displaced six times since 7 October.
"Every time people go back to their homes and begin to rebuild some of their lives even on the rubble of their houses, the occupation sends the tanks back to destroy what is left," he told Reuters via a chat app.
The Israeli military claimed its forces had struck areas in Khan Younis from where around 20 rockets had been fired yesterday. Targets included weapon storage facilities and operational centres, it added.
It said measures were taken before the strikes to ensure civilians were unharmed by enabling them to evacuate from the area, referring to the evacuation orders.
Islamic Jihad, an allied group of Hamas, took credit for firing the rockets.
Hamas and Islamic Jihad continue to stage attacks against Israeli forces operating inside Gaza and fire rockets into Israel.
The Palestinian militant group said Israel has failed to achieve the goals of the war and the group is ready to fight for years.
Efforts to secure a ceasefire and the release of hostages in Gaza have stalled.
Hamas insists any deal must end the war and bring a full Israeli withdrawal from Gaza. Israel claims it will accept only temporary pauses in the fighting until it eradicates Hamas.
