A new group of Israeli hostages were to be freed Tuesday in exchange for Palestinian prisoners as Israel and Hamas embarked on a two-day extension of a truce that has paused the devastating Gaza war.

The temporary cessation of hostilities and releases of captives were hailed as a glimpse of hope after seven weeks of conflict sparked by deadly Hamas attacks that sparked an Israeli military offensive in the Gaza Strip.

The 7:00 am (0500 GMT) deadline for the first phase of the ceasefire to expire passed without major incidents after 11 more Israeli hostages were freed from Gaza and 33 Palestinians walked free from prison in Israel overnight.

But an AFP journalist saw an Israeli tank fire three times in the Sheikh Radwan neighbourhood of Gaza City as Palestinians attempted to make use of the lull to return to their homes.

The Israeli military described the shelling as "warning shots", saying its tank fired as suspected militants approached army positions. At least one person was hurt, the AFP reporter saw. Hamas and UN officials have reported that Israeli fire has killed at least one person since the truce began on November 24.

Key mediator Qatar and the Palestinian militant group Hamas had confirmed the extension of the pause and Israeli media reported the government had received a new list of 10 more hostages who would be freed.

UN Secretary-General Antonio Guterres hailed the ceasefire extension as "a glimpse of hope and humanity in the middle of the darkness of war".

The truce paused fighting that began on October 7 when Hamas militants poured over the border into Israel, killing 1,200 people, mostly civilians, and kidnapping dozens.

Israel's retaliatory ground and air operation in the Gaza Strip has killed almost 15,000 people, mostly civilians, according to the territory's Hamas government.

Despite the truce extension, Israel has vowed to stick to its war aim of destroying Hamas and rescuing all 240 hostages held in the war zone.

- 'Indescribable joy' -

Eleven hostages arrived in Israel late Monday, the military said, adding: "Our forces will accompany them until they are reunited with their families."

Most of the group are dual nationals, with Argentinians, French and Germans among those released, and all 11 were from the Nir Oz kibbutz, the community said.

Images released by the Israeli military showed French-Israeli child Eitan Yahalomi reunited with his mother, who gripped him tightly to her.

Sharon Calderon, the aunt of 16-year-old Sahar and 12-year-old Erez who were released on Monday called for their father Ofer to be released. Two other family members were killed on October 7.

"We've got Erez and Sahar here and we're very, very happy we got them home. We have to get Ofer and the rest of the kidnapped and bring them here," she said. "Bring them home and to be again a big happy family. So let's go, let's bring them back."

Shortly after the arrival of the hostages was confirmed, Israel's prison authority said 33 Palestinian inmates had been released.

In annexed east Jerusalem, prisoner Muhammad Abu Al-Humus called his release "an indescribable joy" and kissed his mother's hand as he entered his home.

"I'm very happy. I hope that others will soon be released -- my friends, my cousins."

Crowds in the West Bank town of Beitunia waved green Hamas flags to greet released prisoners arriving on a coach.

But nearby there were also clashes with Israeli troops by Ofer prison, with Palestinians burning tyres and throwing stones. The Palestinian health ministry said one person was killed.

- Call for Gaza aid -

Under the truce, 50 Israeli hostages have been released in exchange for 150 Palestinian prisoners. Another 19 hostages have been freed under separate deals, including Thai workers and a dual Russian-Israeli citizen.

US National Security Council spokesman John Kirby said that "in order to extend the pause, Hamas has committed to releasing another 20 women and children".

Israel views the truce as temporary to secure hostage releases and plans to continue its war, with the government agreeing a 30.3 billion shekel ($8.2 billion) war budget that will now go to parliament.

But it faces increasing pressure for a more lasting ceasefire and the ramp-up of humanitarian aid to Gaza, where an estimated 1.7 million people have been displaced, according to the United Nations.

This week, US Secretary of State Antony Blinken will pay his third wartime visit to the Middle East, meeting Israeli Prime Minister Benjamin Netanyahu in Tel Aviv and Palestinian president Mahmud Abbas in Ramallah.

"The secretary will stress the need to sustain the increased flow of humanitarian assistance to Gaza, secure the release of all hostages and improve protection to civilians in Gaza," a senior US official said.

Blinken would discuss "the principles he laid out for the future of Gaza and the need to establish an independent Palestinian state," the official added.

- 'Catastrophic' humanitarian plight -

US officials said the United States was sending three military aircraft to Egypt from Tuesday to bring medicine, food and "winter items" for Gaza via northern Egypt.

Inside Gaza, the Hamas-run health ministry said no fuel had arrived for generators at hospitals in the territory's north, despite the truce.

And senior UN official Tor Wennesland warned the humanitarian situation "remains catastrophic".

The truce has allowed residents who fled fighting in northern Gaza to return to Gaza City, which has been ravaged by relentless Israeli bombardment.

People walked or bicycled along debris-lined streets, where the cars were flattened and buildings torn apart.

A clean-up was underway at Gaza's biggest hospital, Al-Shifa, which the Israeli army targeted saying Hamas had used it as a command centre.

"We hope it can soon resume its activities," said Gaza health ministry spokesman Mahmud Hammad.

A limited number of Palestinians have been airlifted to the United Arab Emirates for treatment after crossing from Gaza to Egypt, including seven-year-old Yussef, who gnawed on his nails next to his mother Nouzha Fawzi.

"He was not like that before," she said of Yussef, who suffers from the blood disorder hemophilia.

"Since the war, he no longer speaks much. He is afraid of everything," she added. "He asks me if he will die."