“These developments are further impeding humanitarian access and worsening an already dire situation. At the same time, Hamas goes on firing rockets indiscriminately,” the statement said.

Stressing that civilians must be respected and protected at all times, Mr. Guterres noted that “for people in Gaza, nowhere is safe now."

The Secretary-General reiterated his longstanding urgent appeal for an immediate humanitarian ceasefire and for the release of all hostages.

He also called for the Rafah crossing to be re-opened immediately and for unimpeded humanitarian access throughout Gaza.

Concern for displaced families

Large parts of Rafah have become “a ghost town”, UN Palestine refugee agency UNRWA reported on Tuesday. Some 450,000 people have fled the area over the past week and are seeking shelter where they can, including in rubble and sand dunes.

In New York, UN deputy spokesperson Farhan Haq said displaced families are arriving at sites that lack shelter, latrines and water points.

“However, it is impossible to improve the situation at displacement sites if supplies can't enter Gaza and if we lack the fuel to transport them inside Gaza to the families who need them,” he told journalists attending the daily media briefing at UN Headquarters.

Avert greater tragedy: UNICEF

A senior official with the UN Children’s Fund (UNICEF) said the escalation in Rafah and throughout Gaza has deepened the suffering of hundreds of thousands of boys and girls.

“We cannot accept their plight being livestreamed as collateral damage in a conflict they never chose,” Adele Khodr, UNICEF's regional director for the Middle East and North Africa, said in a statement.

She echoed the Secretary-General’s call to swiftly open border crossings and provide safe humanitarian access so that aid can be delivered to children in Gaza.

“Failure to do so will lead to a tragedy even greater than what we have already witnessed, an outcome we must urgently work to avoid,” she warned.

Aid trucks attacked

Meanwhile, efforts to deliver lifesaving assistance are ongoing amid insecurity and other obstacles.

The UN humanitarian affairs agency, OCHA, said partners reported that work continues to restore health services at Nasser Medical Complex in Khan Younis, which is expected to formally re-open in the coming days.

The hospital began providing dialysis treatment last week to patients who can no longer be treated at An Najjar Hospital in Rafah, which has ceased providing services.

OCHA also reported that on Monday, Israeli settlers in the West Bank attacked aid trucks bound for Gaza.

“The settlers offloaded and vandalised the vehicles at the Tarqumiya checkpoint and near the barrier by Beit ‘Awwa,” the agency said, noting that several trucks were damaged.