Hamas's military wing on Thursday said Israel's objective to eliminate the militant group in Gaza was "doomed to fail", more than two months into war triggered by attacks on Israel.
Abu Obeida, spokesman for Ezzedine al-Qassam Brigades, also said in an audio recording that any further release of hostages held in Gaza depended on a "cessation of aggression".
Neither Israel's continued offensive nor "direct military operations" would bring the hostages home, he said.
"It is not possible to release enemy prisoners alive except by entering into negotiations."
According to Israeli authorities, 129 hostages remain held in Gaza.
Abu Obeida said there was "no alternative" to negotiations, warning that Israeli fire could lead to the deaths of more hostages.
He took aim at Israel's leader, whose "decision... evades facing and recognising the truth".
Shortly after the spokesman's recording, Hamas's armed wing also released a video showing three Israeli hostages, claiming they had since been killed in Israeli strikes.
The bloodiest ever Gaza war began when Hamas attacked Israel on October 7, taking some 250 hostages and killing around 1,140 people, mostly civilians inside Israel, according to an AFP tally based on official figures.
Israel's retaliatory bombardment and ground invasion has killed at least 20,000 people, mostly women and children, according to Gaza's Hamas government.
A truce last month led to the release of over 100 hostages including 80 Israelis freed in exchange for 240 Palestinians held in Israeli prisons.
The head of the Palestinian militant group visited Egypt this week, raising hopes for another truce and deal to free the remaining hostages, though talks have yet to produce a new agreement.
Hamas says Israel bombs Gaza aid crossing, as UN plans vote
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 rejected the allegations as "nothing but blood libel" and "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.
- 'Shameful milestone' -
On Wednesday Gaza's Hamas government said the death toll in the Palestinian territory had hit 20,000, mostly women and children, which United Nations humanitarian chief Martin Griffiths called a "tragic and shameful milestone".
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.
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 health ministry in the Hamas-ruled Palestinian territory 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 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.
Late Wednesday the UN said Israel had ordered the evacuation of large areas of Khan Yunis, the main city in southern Gaza.
Incoming rocket fire set off air raid sirens across southern Israel and as far north as Tel Aviv, but there were no reported casualties.
Hamas's military wing announced it had launched the Tel Aviv-bound "missile barrage in response to the Israeli massacres against civilians".
- 'Beyond catastrophic' -
The UN rights office said the incident in Rimal "raises alarm about the possible commission of a war crime", and added the men were killed in front of their family members.
"The details and circumstances of the killings are still under verification," the UN said.
Legal experts have previously told AFP that both sides could be accused of committing war crimes.
There are no longer any functional hospitals in the northern Gaza Strip, the World Health Organization (WHO) said Thursday, after it led missions to two badly damaged hospitals, Al-Shifa and Al-Ahli.
"Our staff are running out of words to describe the beyond catastrophic situation facing remaining patients and health workers," said Richard Peeperkorn, the WHO Gaza and West Bank representative.
Diplomats called for more assistance to reach the territory.
British Foreign Secretary David Cameron, speaking on a visit to Egypt, said: "Everything that can be done must be done to get aid into Gaza, to help people in the desperate situation that they're in."
French President Emmanuel Macron was in Jordan on Thursday to discuss with King Abdullah II "joint work on humanitarian and medical aid for the civilian population of Gaza", according to the French presidency.
France called for the protection of civilians and "a truce leading to a humanitarian ceasefire", Macron said on Wednesday.
- 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.
The United Arab Emirates is sponsoring a proposed resolution which has already been watered down to secure compromise, according to a draft version seen by AFP.
It calls for "the urgent suspension of hostilities to allow safe and unhindered humanitarian access, and for urgent steps towards a sustainable cessation of hostilities".
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.
The Palestinian group's military wing said on Thursday that Israel's objective to eliminate it was "doomed to fail" and that any further releases of hostages depended on a "cessation of hostilities".
US President Joe Biden said of a fresh hostage release deal: "There's no expectation at this point. But we are pushing it."
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.
Entire Gaza faces 'crisis or worse' hunger level: UN
Every single person in war-torn Gaza is expected to face high levels of acute food insecurity in the next six weeks, a report by the UN's hunger monitoring system said Thursday.
The five-scale food insecurity classification, known as the IPC, forecast in its "most likely scenario" that by February 7 "the entire population in the Gaza Strip (about 2.2 million people)" would be at "crisis or worse" levels of hunger.
"This is the highest share of people facing high levels of acute food insecurity that the IPC initiative has ever classified for any given area or country," it said.
International alarm has mounted over the plight of Gazans enduring daily bombardment, food and water shortages and mass displacement.
The Integrated Food Security Phase Classification (IPC) rates hunger levels from one to five.
The report warned that some 50 percent of the population are forecast to be in the "emergency" phase -- which includes very high acute malnutrition and excess mortality -- by February 7.
And "at least one in four households", over half a million people, would be facing "Phase 5" catastrophic conditions, it predicted.
"Even though the levels of acute malnutrition and non-trauma related mortality might not have yet crossed famine thresholds, these are typically the outcomes of prolonged and extreme food consumption gaps," it said.
International humanitarian organization CARE said the figures were "alarming".
The war in Gaza began when its Islamist rulers Hamas infiltrated Israel on October 7 and killed around 1,140 people, mostly civilians, and abducting 250, according to an AFP tally based on Israeli figures.
Israel responded with a relentless air and ground campaign. The Hamas government's media office in the Gaza Strip said Wednesday at least 20,000 people have been killed, among them 8,000 children and 6,200 women.