Israel bombed a newly reopened aid crossing point on Thursday, Hamas authorities said, hours before the United Nations Security Council was to make another attempt to pass a much-delayed resolution on pausing the Gaza fighting.
Separate diplomatic efforts continued for a fresh truce and hostage release deal in the worst-ever Gaza war.
The United Nations human rights office in Ramallah said it had received reports that Israeli troops had "summarily killed" at least 11 unarmed Palestinian men in Gaza City's Rimal neighbourhood this week.
An Israeli official, speaking on condition of anonymity, rejected the allegations as "yet another example of the partisan and prejudiced approach against Israel" by the UN body.
Israel has been under increasing pressure from allies, including the United States which provides it with billions of dollars in military aid, to protect civilians.
The UN estimates 1.9 million Gazans are displaced, out of a population of 2.4 million.
With their homes destroyed, they are living in crowded shelters and struggling to find food, fuel, water and medical supplies. Diseases are spreading, and communications have been repeatedly cut.
On Thursday a UN monitoring system said every single person in Gaza is expected to face high levels of acute food insecurity in the next six weeks.
- Strike halts aid -
The war began on October 7 with an unprecedented attack by Hamas militants. They broke through Gaza's militarised border to kill around 1,140 people in Israel, mostly civilians, according to an AFP tally based on Israeli figures.
They also abducted about 250 people.
Vowing to destroy Hamas, Israel began a relentless bombardment of targets in Gaza, alongside a ground invasion, which Gaza's Hamas government on Wednesday said has killed at least 20,000, mostly women and children.
Munir al-Bursh, director of the Hamas health ministry, was among the latest to be wounded while his daughter was killed in an Israeli bombardment on Jabalia, in northern Gaza, the ministry said.
According to the UN, the number of aid trucks entering Gaza is well below the daily pre-war average.
After weeks of pressure, Israel approved the temporary reopening of the Kerem Shalom crossing on Friday to enable aid deliveries directly to Gaza, rather than through the Rafah crossing from Egypt.
On Thursday an Israeli strike killed Bassem Ghaben, the head of the Palestinian side of Kerem Shalom, the crossings authority and the Hamas health ministry said.
Three other people were also killed when Israeli aircraft targeted the infrastructure, they said.
Israeli officials did not immediately respond to requests from AFP for comment.
The UN secretary-general's spokesman, Stephane Dujarric, said the United Nations agency for Palestinian refugees, UNRWA, was "unable to receive (aid) trucks" via Kerem Shalom following the "drone strike" and the World Food Programme suspended operations at the crossing.
Dujarric's comments came after Israeli President Isaac Herzog said Israel could enable "even 400 trucks a day" of aid and blamed the UN for failing to bring more.
The army said its aircraft struck 230 targets in Gaza over the past day, including a rocket launch site, while ground forces had found weapons inside a school near Gaza City.
Israel has repeatedly accused Hamas of using schools, mosques, hospitals and vast tunnel systems beneath them as military bases -- charges the group denies.
The army says 138 of its soldiers have been killed in Gaza.
On Thursday military spokesman Daniel Hagari said troops have killed more than 2,000 Palestinian militants since a one-week ceasefire ended on December 1. He did not elaborate on the source of his figures.
- 'Beyond catastrophic' -
The UN rights office said "details and circumstances" the killings in Rimal are still being verified but it "raises alarm about the possible commission of a war crime".
The men were killed in front of their family members, it said.
Legal experts have previously told AFP that both sides could be accused of committing war crimes.
Diplomats visiting the region called for more assistance to reach Gaza.
British Foreign Secretary David Cameron, speaking in Egypt, said: "Everything that can be done must be done to get aid into Gaza".
French President Emmanuel Macron was in Jordan on Thursday to discuss with King Abdullah II "joint work on humanitarian and medical aid" for Gaza's civilians, according to the French presidency.
- Controversial wording -
The UN Security Council was due to try for a fourth day Thursday to pass a resolution calling for a halt in fighting.
Israel has rejected the term "ceasefire", and Washington has used its veto twice to thwart resolutions opposed by Israel since the start of the war.
A sticking point has been calls for UN monitoring of aid entering Gaza.
"Israel has had, understandably so, a role in the inspection regime -- a key role, a pivotal role -- and we understand and respect that," US National Security Council spokesman John Kirby told reporters.
Hopes that Israel and Hamas could be inching towards another truce and deal to free the remaining 129 hostages had risen this week as the head of the Palestinian militant group visited Egypt and talks took place in Europe.
However, the stated positions of Israel and Hamas remain far apart.
Hamas's military wing said on Thursday that Israel's objective to eliminate it was "doomed to fail" and that further releases of hostages depended on a "cessation of hostilities".
Qatar, backed by Egypt and the United States, last month helped broker a first week-long truce that saw 105 hostages released, including 80 Israelis freed in exchange for 240 Palestinian prisoners.
Displaced Gazans are pleading for a ceasefire.
"My message is to put an end to this humiliation," said Fuad Ibrahim Wadi, who found refuge at a greenhouse in Rafah. "This war does nothing but destroy. Enough is enough."
The war has sparked fears of wider conflict.
There have been regular exchanges of fire over the Lebanon border, and missiles from Iran-backed Yemeni rebels have disrupted Red Sea shipping.
Israeli strikes killed a woman in a south Lebanon village on Thursday, Lebanese media and rescuers said, with retaliatory attacks by Hezbollah militants wounding two civilians, according to Israel's military.
