US President Joe Biden and his Israeli counterpart Benjamin Netanyahu have held their first phone call in a month, amid warnings of an “imminent famine” in northern Gaza.

It comes as a group of aid agencies warned that an estimated 70% of the population in northern Gaza faced catastrophic hunger, and that virtually everyone in the besieged strip is struggling to get enough food.

The European Union’s top diplomat also blamed Israel for the crisis on Monday, saying an impending famine in Gaza was “entirely man-made”.

Meanwhile, amid talk of tension between the US and Israel, White House national security adviser, Jake Sullivan, confirmed that Mr Netanyahu had held a phone call – their first in 31 days.

He said they had agreed to send a team of Israeli officials to Washington to discuss with members of Mr Biden’s team to hear US concerns about a possible military assault on the southern Gazan city of Rafah.

He said the talks, expected to involve military, intelligence, and humanitarian experts, were set to be held in the coming days.

But he stressed that the US felt a major ground operation in Rafah would be a “mistake” and that Mr Biden had warned Mr Netanyahu against it.

“It would lead to more innocent civilian deaths, worsen the already dire humanitarian crisis, deepen the anarchy in Gaza, and further isolate Israel internationally,” Mr Sullivan added.

“Israel has not presented us or the world with a plan for how or where they would safely move those civilians, let alone feed and house them and ensure access to basic things like sanitation.”

In other developments in the Israel-Hamas war:

• Israeli forces launched another raid on the Gaza Strip’s largest hospital on Monday, saying Hamas militants had regrouped there;

• They also said they had killed a Hamas commander who was armed and hiding inside the medical centre;

• It emerged Israel had urged the top UN court to reject the latest request by South Africa for interim orders to prevent starvation in Gaza;

• A top UN aid official for Palestinian areas called for an opening of “all roads” into Gaza to help avert the potential famine.

On Monday, a new report from the Integrated Food Security Phase Classification warned of an “imminent famine” in northern Gaza.

The group, a partnership of more than a dozen governments, UN aid and other agencies that determine the severity of food crises, said virtually everyone in Gaza was struggling to get enough food.

It also said that some 210,000 people in the north were in “Phase 5”, its highest category, referred to as “catastrophic hunger”.

A looming Israeli ground attack in Rafah would worsen the crisis, it warned, claiming it would drive around half of the 2.3 million people in Gaza into Phase 5.

On Monday, Josep Borrell, the European Union’s foreign policy chief, accused Israel of weaponising food to provoke famine.

“In Gaza we are no longer on the brink of famine, we are in a state of famine, affecting thousands of people,” he said at the opening of a conference on humanitarian aid for Gaza in Brussels.

“Trucks are stopped. People are dying, while the land crossings are artificially closed,” he said.

Aid agencies say they have struggled to get enough aid in because of a burdensome Israeli process to import humanitarian aid, and that the continuing conflict has made distribution in the north of Gaza virtually impossible.

Israel says there are “no limits on the amount of aid that can go into Gaza”.

The US and other countries have carried out airdrops in recent days and a sea corridor has just opened up.

However, aid groups have said those efforts are costly and inefficient and are no substitute for Israel opening up more land routes.

It comes as Israeli forces launched another raid on the Gaza Strip’s largest hospital on Monday, saying Hamas militants had regrouped there and had fired on them from inside the site where Palestinian officials say tens of thousands of people have been sheltering.

The army last raided al Shifa Hospital in November after claiming that Hamas maintained an elaborate command centre within and beneath the facility.

However, the Israel Defence Forces (IDF) and Israel Securities Authority (ISA) said military activity had not stopped and they had launched a “precise operation to thwart terrorist activity”.

The IDF said it killed a Hamas commander who was armed and hiding inside the medical centre, and that one of its own soldiers was killed in the operation.

Palestinian authorities described the raid as a “war crime” that had resulted in multiple casualties.

Separately, on Monday, the US said Israel had killed Hamas number three, Marwan Issa, in an operation last week.

A spokesperson for the IDF said they had “no comment on the matter”.

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Later on Monday, it emerged that Israel has urged the top UN court to reject the latest request by South Africa for interim orders to prevent starvation in Gaza as part of a case accusing Israel of breaching the Genocide Convention with its military offensive against Hamas.

In a written response published on Monday by the International Court of Justice, Israel said that claims by South Africa in its request filed earlier this month were “wholly unfounded in fact and law, morally repugnant, and represent an abuse both of the Genocide Convention and of the Court itself”.

Israel fervently denies that its military campaign in Gaza amounts to a breach of the Genocide Convention.

It acknowledged in its written response to South Africa’s request that there are “also tragic and agonising civilian casualties in this war”.

“These realities are the painful result of intensive armed hostilities that Israel did not start and did not want,” it said.

No date has been set for judges to rule on the South African request.

At hearings in January, lawyers for Israel argued that the war in Gaza was a legitimate defence of its people and that it was Hamas militants who were guilty of genocide.

After the hearings, the court ordered Israel in late January to do all it could to prevent death, destruction and any acts of genocide in Gaza, but stopped short of ordering an end to the military offensive triggered by the deadly 7 October incursion into southern Israel by Hamas.