JERUSALEM - A UN agency warned it could be forced to stop aid operations in war-riven Gaza on Wednesday due to dwindling fuel supplies, as calls mounted for a humanitarian "pause" in fighting.
After 18 days of withering Israeli air strikes and a near-total land, sea and air blockade of the Palestinian territory, UN refugee agency UNRWA warned operations were at breaking point.
"If we do not get fuel urgently, we will be forced to halt our operations in the Gaza Strip," said the UN agency, which provides aid to 600,000 displaced Gazans.
Israel launched its campaign in response to an unprecedented cross-border attack by Hamas militants on October 7.
Gunmen from the Palestinian group poured into Israel from Gaza, killing more than 1,400 people and taking 222 hostages, according to Israeli authorities.
Israeli Prime Minister Benjamin Netanyahu has promised to "eliminate Hamas" and ensure it can no longer threaten Israeli civilians.
But there is growing international unease about the impact of Israel's "Operation Swords of Iron", which has killed thousands of Palestinians.
Gaza's Hamas-run health ministry claims 5,791 people have been killed in the war so far, many of them children.
Tuesday's toll was more than 700 people, the Hamas-run ministry said, with the UN saying it was the highest reported in a single day since the war began.
AFP has not been able to independently verify these figures.
Aid agencies report hospitals are overwhelmed, generators lack fuel and shelters are heaving under the weight of an estimated 1.4 million displaced -- more than half the population.
Since the war began a few dozen trucks with essential supplies have been allowed to cross the Egyptian border into Gaza, far fewer than necessary according to aid agencies.
The Palestine Red Crescent said Tuesday it had received the fourth batch of humanitarian aid, consisting of eight trucks.
The supplies have included medicines, food and water, but not fuel, which Israel fears could end up in Hamas's hands.
- 'Epic suffering' -
UN Secretary-General Antonio Guterres on Tuesday said Gaza was now seeing "epic suffering" while calling on Israel to safeguard civilians.
"The relentless bombardment of Gaza by Israeli forces, the level of civilian casualties, and the wholesale destruction of neighbourhoods continue to mount and are deeply alarming," he told the UN Security Council in New York.
"I am deeply concerned about the clear violations of international humanitarian law that we are witnessing in Gaza," he said. "Let me be clear: No party to an armed conflict is above international humanitarian law."
That warning drew an angry response from Israeli Foreign Minister Eli Cohen, who cited the graphic ways in which Israeli civilians had been killed by Hamas, and demanded: "Mr secretary-general, in what world do you live?"
Israel and its allies have so far rebuffed calls for a blanket ceasefire, which the White House says would only benefit Hamas.
But US officials have indicated that a more limited "humanitarian pause" in certain areas could be on the table to allow aid in and to safeguard civilians.
President Joe Biden has said a full ceasefire could only be considered if and when Hamas releases the hundreds of hostages it is keeping captive in Gaza.
Meanwhile, Israel has continued massing tens of thousands of troops around Gaza ahead of an expected ground offensive.
That operation appears to have been stalled by concerns about objectives, the fate of hostages, civilian casualties and the difficulties of fighting in a densely populated area riven with underground tunnels.
"There are a lot of obstacles," one Israeli soldier serving with unit 601 of the military engineering corps told AFP on condition of anonymity.
"The enemy is spraying rockets and other things that I cannot detail to prevent us from progressing."
- 'First objective' -
So far Hamas has only released four hostages, including 85-year-old Israeli Yocheved Lifshitz.
Reuniting with family after more than two weeks in Hamas captivity, on Tuesday she spoke about the "hell" of her abduction.
She recalled how gunmen raided her kibbutz home, throwing her over the back of a motorbike and beating her as they stole away into Gaza.
"They didn't break my ribs, but they hurt me very much," she told reporters.
She and 79-year-old Nurit Cooper were released on "compelling humanitarian" grounds, according to Hamas, following mediation by Qatar and Egypt.
Both of their octogenarian husbands are still in Gaza.
During a visit to Israel and the Palestinian territories on Tuesday, French President Emmanuel Macron said freeing hostages must be "the first objective" of Israel's military campaign.
He also called for the international coalition fighting the Islamic State group to be expanded to "also fight against Hamas".
Throughout the war, Hamas has continued to launch rocket attacks and raids into Israel.
Warning sirens wailed across central Israel on Tuesday afternoon and the Iron Dome air defence system was seen intercepting missiles near Tel Aviv, AFP correspondents said.
The Israeli military also said it had "targeted a cell of (Hamas) divers" that tried "to infiltrate Israeli territory by sea in the area of kibbutz Zikim" just north of Gaza.
Amid fears that the Israel-Hamas conflict is spilling over into the broader Middle East, US Secretary of State Antony Blinken on Tuesday warned Hamas ally Iran that the United States would respond "decisively" to any attack by its proxies.
"The United States does not seek conflict with Iran. We do not want this war to widen," he said after several reported attacks on US forces in Iraq by Iran-back groups.
"But if Iran or its proxies attack US personnel anywhere, make no mistake. We will defend our people, we will defend our security -- swiftly and decisively," Blinken told a UN Security Council session.
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By Valerie Leroux And Claire Gounon