Fighting raged on Sunday between Hamas militants and Israeli forces in parts of north Gaza and Israeli air strikes killed dozens of Palestinians in the enclave's centre, witnesses said, as a report of a tentative hostage release deal was denied.

The Washington Post reported that Israel and Hamas had reached a tentative U.S.-brokered agreement to free dozens of women and children held hostage in Gaza in exchange for a five-day pause in their war, citing people familiar with the matter.

It said the hostage release could begin within the next several days, barring last-minute hitches. All parties would freeze combat operations for at least five days while 50 or more hostages are released in groups every 24 hours, the Post reported. Hamas took about 240 hostages during its deadly cross-border rampage into Israeli communities on Oct. 7.

The pause is also intended to allow a significant amount of humanitarian aid in, the newspaper reported, adding that the outline of the deal was put together during weeks of talks in Qatar.

But both Israel's prime minister and U.S. officials said no agreement had been hammered out yet, with a White House spokesperson saying efforts were continuing to clinch a deal.

The Post's report came as Israel appeared to be preparing to expand its offensive against Hamas militants to densely populated Gaza's southern half after air strikes killed dozens of Palestinians, including civilians reportedly sheltering at two schools.

Israeli forces invaded late last month after a devastating aerial blitz in response to Hamas's attack, and say they have wrested control of large areas of the north and northwest around Gaza City.

But guerrilla-style Hamas resistance remains fierce in pockets of the heavily urbanised north including parts of Gaza City and the sprawling Jabalia and Beach refugee camps, according to Hamas and local witnesses.

Witnesses reported heavy fighting overnight between Hamas gunmen and Israeli ground forces trying to advance into Jabalia, the largest of the enclave's camps with nearly 100,000 people, most of whom rejected Israeli appeals to evacuate to the south.

Jabalia has come under repeated Israeli bombardment that has killed scores of civilians, Palestinian medics say, with Israel saying the strikes have killed many militants harbouring there.

AIR STRIKES IN CENTRAL GAZA

In the centre of the narrow coastal enclave, Palestinian medics said 31 people were killed, including two local journalists, in Israeli air strikes on the Bureij and Nusseirat refugee camps. Another air strike killed a woman and her child overnight in the southern city of Khan Younis, they said.

In Nasser Hospital in Khan Younis, dozens of Palestinians marched to a funeral for 15 residents killed in an Israeli strike on an apartment block on Saturday. “Our youth are dying, women and children are dying, where are the Arab presidents?" said Heydaya Asfour, a relative of some of the dead.

The Israeli army says Hamas uses residential and other civilian buildings as cover for command centres, weapons, rocket launchpads and a vast underground tunnel network. The Islamist movement denies using human shields to wage war.

Hamas's armed wing, the Al Qassam Brigades, said militants killed six soldiers at close range in the village of Juhr al-Dik just east of Gaza City after ambushing them with an anti-personnel missile and closing in with machine guns.

Seven Israeli soldiers were killed in the fighting on Saturday, the military said, without giving details.

Israel vowed to destroy Hamas after its Oct. 7 attack in which around 1,200 Israelis, mostly civilians, were killed, the deadliest day in the country's 75-year history.

As the conflict entered its seventh week, there was no sign of a let-up, despite international appeals for "humanitarian pauses" to enable untrammelled, safe deliveries of aid to civilians who lack food, drinking water and medical care

Gaza's Health Ministry raised its death toll from the unrelenting Israeli bombardment to 12,300, including 5,000 children.

Israel's blitz has reduced swathes of the north to rubble, while some two-thirds of Gaza's population of 2.3 million have been displaced to the south.

'DEATH ZONE' AT GAZA'S BIGGEST HOSPITAL

A team led by the World Health Organization that visited Al Shifa, Gaza's biggest hospital on Saturday described it as a "death zone", days after Israeli forces seized the premises to root out an alleged Hamas command centre underneath it.

The WHO team reported signs of gunfire and shelling and a mass grave at Al Shifa's entrance, and said it was making plans for the immediate evacuation of 291 remaining patients, including the war-wounded and 32 premature babies in critical condition, as well as 25 staff.

Muhammad Zaqout, Gaza's general director of hospitals, told Al Jazeera TV that WHO had told him the 32 infants would be transferred to nurseries in south Gaza.

Hundreds of other patients, staff and displaced people who were sheltering in Al Shifa left on Saturday, with Palestinian health officials saying they were ejected inhumanely by Israeli troops and the military saying the departures were voluntary.

Elsewhere in the north, Commissioner-General Philippe Lazzarini of UNRWA, the U.N. agency for Palestinian refugees, said on Saturday that Israel had bombarded two UNRWA schools in Jabalia, one of which was sheltering 4,000 displaced people.

"Dozens reported killed including children," he said in a post on social media platform X. "Second time in less than 24 hours schools are not spared. ENOUGH, these horrors must stop."

A Hamas spokesperson said 200 people had been killed or injured at the schools. The Israeli military did not comment.

After air-dropping leaflets earlier in the week, Israel on Saturday again warned civilians in parts of southern Gaza to relocate as it girds for an onslaught from the north.

An Israeli offensive in the south could compel hundreds of thousands of Palestinians who fled Gaza City to uproot again, along with residents of Khan Younis, a city of more than 400,000, compounding an already dire humanitarian crisis.

But an advance into southern Gaza may prove more complicated and deadlier than the north, with Hamas militants dug into the Khan Younis region, a power base of Gaza political leader Yahya Sinwar, a senior Israeli source and two top ex-officials said.