Vital fuel supplies needed to run hospitals and provide water to Gaza are on the verge of running out, a United Nations agency has said, exacerbating the crisis on a densely populated territory already facing severe shortages.

The warning, from the main UN agency working in Gaza, that it will be forced to halt its operations by Wednesday evening due to a lack of fuel comes as Israeli airstrikes on the besieged strip killed more than 700 people in 24 hours, according to Palestinian officials.

“If we do not get fuel urgently, we will be forced to halt our operations in the #GazaStrip as of tomorrow night,” the UN Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) wrote on social media Tuesday. Gaza needs at least 160,000 liters (42,267 gallons) of fuel a day for basic necessities, UNRWA spokesperson Juliette Touma said.

Doctors in overwhelmed hospitals on the brink of shutting down have repeatedly warned that waves of new patients injured in the daily bombings and babies relying on oxygen supplies will die if fuel is not brought in.

A fierce row has meanwhile broken out between Israel and the UN, after Secretary General António Guterres appealed on Tuesday for “an immediate humanitarian ceasefire,” saying “the clear violations of international humanitarian law” are being witnessed in Gaza.

“Protecting civilians does not mean ordering more than one million people to evacuate to the south, where there is no shelter, no food, no water, no medicine and no fuel – and then continuing to bomb the south itself,” Guterres said.

He called Hamas’ October 7 murder and kidnap rampage “appalling” but said it “cannot justify the collective punishment of the Palestinian people. Excellencies, even war has rules.”

“It is important to also recognize the attacks by Hamas did not happen in a vacuum,” Guterres said. “The Palestinian people have been subjected to 56 years of suffocating occupation. They have seen their land steadily devoured by settlements and plagued by violence; their economy stifled; their people displaced and their homes demolished.”

Those remarks sparked an angry response from Israeli officials. Israel’s ambassador to the UN, Gilad Erdan, called on Guterres “to resign immediately” after his remarks and wrote on social media that he was “not fit to lead the UN.”

Erdan then said on Wednesday his country will block visas for United Nations officials. He told the Israeli Army Radio channel that his government had already rejected an application by the UN Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator, Martin Griffiths.

“It’s time we teach them a lesson,” added Erdan.

Israeli Foreign Minister Eli Cohen, who was at the United Nations on Tuesday, said he would not meet with Guterres and that “there is no place for a balanced approach.”

“Hamas must be erased off the face of the planet!” Cohen wrote on X, formerly known as Twitter.

A deepening crisis

The deteriorating health environment, lack of sanitation, and consumption of dirty, salty water in Gaza is raising fears of a health crisis in which people could start dying from dehydration as the water system collapses while bombs continue to rain down.

Just eight out of 20 aid trucks scheduled to cross into Gaza on Tuesday made the journey, UNRWA said. No specific reason was provided as to why the other 12 trucks didn’t make it through the Rafah crossing.

Since the start of the Israeli siege two weeks ago, six hospitals in Gaza have been forced to close due to a lack of fuel, the World Health Organization said on Tuesday.

Among those at risk of dying or suffering medical complications are “1,000 patients dependent on dialysis” and “130 premature babies” and other vulnerable patients “who depend on a stable and uninterrupted supply of electricity to stay alive,” WHO said in a statement.

The Israel Defense Forces (IDF) on Tuesday ruled out any fuel being allowed to enter Gaza, saying Hamas would co-opt fuel for its operational infrastructure and to continue its rocket attacks.

Israel’s leadership has vowed to wipe out Hamas in response to its October 7 deadly terror attacks and kidnap rampage in which 1,400 people, mostly civilians, were killed and more than 200 taken hostage.

In the wake of the assault, Israel launched a sustained aerial bombardment of Gaza that Palestinian health officials say has now killed more than 5,000 people.

More than 700 of those were killed in Gaza in the previous 24-hour period, the highest daily number published since Israeli strikes against what it called Hamas targets in Gaza began two and a half weeks ago, according to the Palestinian Ministry of Health in Ramallah on Tuesday.

Those killed included 305 children, 173 women and 78 elderly individuals, the ministry said.

Some two million people are crammed into the 140 square mile coastal strip that makes up Gaza, half of whom are children.

No international consensus

As the humanitarian crisis in Gaza deepens, the international community has struggled to find consensus.

The United States, Israel, Qatar, Egypt and Hamas are engaged in the ongoing deliberations. Four hostages – two American and two Israeli – have been freed so far. But the hope now is to reach a deal for a bigger group of hostages to be released at once.

Israel has so far held off on making a ground incursion into Gaza, and the US has pressed Israel to further delay to allow for the release of more hostages held by Hamas.

Foreign Minister Cohen said outside the UN Tuesday it was Israel’s mission to bring the hostages home.

“While we are still here, there are babies that are in captivity, twins, holocaust survivors, and we have one mission: To bring them home,” Cohen said.

Israeli Prime Minister Benjamin Netanyahu appeared to tell soldiers on Tuesday a ground offensive was still on track, saying, “we stand before the next stage, it is coming.”