GAZA STRIP, Palestinian Territories, Dec 3, 2023 (BSS/AFP) - Israel struck Gaza targets Sunday in its war on Hamas sparked by the October 7 attacks as international concern mounted over the spiralling civilian death toll on the third day after the end of a week-long truce.

More than 15,200 people have been killed in the besieged Palestinian territory, according to Hamas, in more than eight weeks of fighting that resumed after the ceasefire ended early Friday.

The UN humanitarian agency OCHA said at least 160 Palestinian deaths were reported in two incidents in northern Gaza Saturday: the bombing of a six-storey building in Jabaliya refugee camp, and of an entire block in a Gaza City neighbourhood.

Repeated bursts of heavy automatic weapons fire were heard Sunday over an AFPTV livecam which showed dark smoke rising over northern Gaza.

Gaza's Hamas government on Saturday said 240 people had been killed since the truce expired.

"I cannot find words strong enough to express our concern over what we're witnessing," the head of the World Health Organization, Tedros Adhanom Ghebreyesus, said Sunday on X, formerly Twitter, demanding a "Ceasefire. NOW."

Israel has vowed to destroy Hamas, while the militant group has ruled out more hostage releases until a permanent ceasefire is agreed.

"We have said it from day one: the price to pay for the release of Zionist prisoners will be the release of all our prisoners -- after a ceasefire," Saleh al-Arouri, deputy head of Hamas's politburo, said on Saturday evening.

Israel's army, after focusing on northern Gaza in recent weeks, has struck more targets in the territory's south and issued warnings to Palestinians trapped there to seek what it said would be safe zones.

Hamas and Islamic Jihad announced "rocket barrages" against multiple Israeli cities and towns including Tel Aviv, and Israel said two of its soldiers had died in combat, the first since the truce ended.

In a summary of activity issued on Sunday, the military said a drone strike had "eliminated" five Hamas militants. 

Fighter jets and helicopters had also struck "tunnel shafts, command centres and weapons storage facilities" while naval forces hit Hamas vessels and weapons, it said.

At least seven people were killed in an Israeli bombing early Sunday near Gaza's southern border with Egypt, the Hamas government said.

- 'Too many' innocents killed -

Israel's ally the United States, which provides it with billions of dollars in military aid annually, has intensified calls for the protection of Gaza's civilians.

"Too many innocent Palestinians have been killed," Vice President Kamala Harris told reporters at UN climate talks in Dubai.

In a new estimate, OCHA said around 1.8 million people in Gaza, roughly 75 percent of the population, had been displaced, many to overcrowded and unsanitary shelters.

Nasser hospital in the southern Gaza city of Khan Yunis overflowed with both the wounded and the dead.

Jumana Murad said her son Mohammad, 19, was killed as he tried to help women and children out of a tent inside a school.

"A piece of shrapnel hit him in the head," she told AFP before bursting into tears.

Tedros said a WHO team visited Nasser hospital and found it with 1,000 patients, three times its capacity. Some were being treated on the floor, "screaming in pain," he said.

Gazans are short of food, water and other essentials, and many homes have been destroyed. 

- Call for hostages return -

The war broke out when Hamas militants burst through Gaza's militarised border into Israel on October 7 and killed about 1,200 people, mostly civilians, while also taking around 240 hostages, according to Israeli authorities.

Israel has vowed to eliminate Hamas and unleashed an air and ground campaign that has killed more than 15,200 people, mostly women and children, Gaza's Hamas authorities say.

The truce, brokered by Qatar with support from Egypt and the United States, led to the release of 80 Israeli hostages in exchange for 240 Palestinian prisoners.

On Saturday Prime Minister Benjamin Netanyahu's office said Israeli negotiators were being withdrawn from Qatar "following the impasse in the negotiations".

The Israeli army said 137 hostages were still being held in Gaza.

Defence Minister Yoav Gallant said Saturday that more military action was needed to "create the conditions that push (Hamas) to pay a heavy price, and that is in the release of hostages".

Israeli hostages released from Gaza talked publicly on Saturday for the first time, urging their government to secure the release of the remaining captives.

"The moral obligation of this government is to bring them home immediately, without hesitation," said Yocheved Lifschitz, 85, who was freed by Hamas before the truce deal. 

French President Emmanuel Macron appealed for "stepped-up efforts to reach a lasting ceasefire" to free all hostages, allow in more aid and to assure Israel of its security.

He said Israel's war aim of destroying Hamas needed to be defined more precisely. "What is the total destruction of Hamas, and does anyone think it's possible? If it is, the war will last 10 years," Macron said.

- 'Total victory' -

But Netanyahu said the war would continue "until we achieve all its aims" and soldiers had prepared during the truce "for total victory against Hamas".

"There is no way to win except by continuing the ground campaign," Netanyahu said, vowing that Israel would be "observing international law".

US Defense Secretary Lloyd Austin on Saturday drew on his experience fighting the Islamic State group in urging Israel to protect non-combatants.

"The lesson is that you can only win in urban warfare by protecting civilians," he told a forum in California.

Among the targets hit Saturday in Khan Yunis was a Doha-funded housing development.

At almost exactly the same time Israeli negotiators pulled out of the Qatar talks, bombs pounded the modern-looking yellow apartment blocks one by one.

Most Gazans are trapped but an Egyptian border crossing, after a closure on Friday, reopened to enable 880 foreign and dual nationals to cross along with 13 injured people, the UN said.

Aid trucks with food, medical supplies and other essentials also entered, the UN said.

Violence has also escalated in the Israeli-occupied West Bank, where the number of Palestinians killed by either soldiers or Israeli settlers during the war exceeds the entire toll of around 235 last year in the Israeli-Palestinian conflict.