As talks continued in Qatar, the Israeli military carried out strikes across the enclave, killing at least 23 people on Thursday, Palestinian medics said.
The deaths brought to 76 the number of people killed by Israeli strikes across the Gaza Strip in the past 24 hours, according to the territory's health ministry.
Qatar, the US and Egypt are making a major push to reach a deal to halt fighting in the 15-month conflict and free remaining hostages held by Islamist group Hamas before US President Joe Biden leaves office.
President-elect Donald Trump has warned there will be "hell to pay" if the hostages are not released by his inauguration on January 20.
On Thursday, a Palestinian official close to the mediation effort said the absence of a deal so far did not mean the talks were going nowhere and this was the most serious attempt so far.
Palestinian health officials say more than 46,000 people have been killed in the Gaza war. (AP PHOTO)
"There are extensive negotiations, mediators and negotiators are talking about every word and every detail. There is a breakthrough when it comes to narrowing old existing gaps but there is no deal yet," he told Reuters, without giving further details.
Another Palestinian official confirmed progress had been made during the talks but cited a new Israeli condition that could undermine reaching a deal.
"However, Israel still insists on keeping a 1km landscape along the eastern and northern borders of the Gaza Strip, which will restrict the return of residents to their homes and represent a retreat from what it (Israel) had agreed upon in July," the official said.
"This undermines reaching an agreement and the mediators are exerting effort to convince Israel to return to what had been agreed in the past," the official, who asked not to be identified due to the sensitivity of the talks, told Reuters.
There was no Israeli comment on the allegations.
On Tuesday, Israel said it was fully committed to reaching an accord to return hostages but faces obstruction from Hamas.
The two sides have been at an impasse for a year over two key issues.
Hamas has said it will only free its remaining hostages if Israel agrees to end the war and withdraw all its troops from Gaza.
Israel says it will not end the war until Hamas is dismantled and all hostages are free.
On Thursday, the death toll from Israel's military strikes included eight Palestinians killed in a house in Jabalia, the largest of the Gaza Strip's eight historical refugee camps.
Nine others, including a father and his three children, died in two air strikes on two houses in central Gaza, health officials said.
Dozens of people arrived at the hospital in Deir al-Balah in central Gaza to mourn their dead relatives and take their bodies, wrapped in white shrouds, to graves.
"There is no safety in the country, at all, not for a child, a woman, an old person, not for stones or trees, animals or birds or anything. Everyone is targeted, without prior warning," said resident Adel al-Mansi.
Later on Thursday, six Palestinians were killed in two separate air strikes, four of them at a school sheltering displaced families near Jabalia in the northern Gaza Strip, medics said.
There was no Israeli military comment on Thursday's incidents.
In an address delivered by an aide, Pope Francis stepped up his recent criticisms of Israel's military campaign, calling the humanitarian situation in the Gaza Strip "very serious and shameful".
"We cannot accept that children are freezing to death because hospitals have been destroyed or a country's energy network has been hit."
More than 46,000 people have been killed in the Gaza war, according to Palestinian health officials.
Much of the enclave has been laid waste and most of the territory's 2.1 million people have been displaced multiple times and face acute shortages of food and medicine, humanitarian agencies say.
Israel launched its assault on Gaza after Hamas fighters stormed southern Israel on October 7, 2023, killing 1200 people and capturing more than 250 hostages, according to Israeli tallies.
