By James Mackenzie and Nidal al-Mughrabi

JERUSALEM/CAIRO (Reuters) - The Palestinian militant group Hamas is expected to release the first hostages under a Gaza ceasefire deal on Sunday, Prime Minister Benjamin Netanyahu's office said on Friday, after 15 months of war that demolished the enclave.

If successful, the ceasefire would halt fighting that has razed much of heavily urbanised Gaza, killed over 46,000 people, and displaced most of the tiny enclave's pre-war population of 2.3 million several times over, according to local authorities.

It could also ease hostilities in the Middle East, where the Gaza war spread to include Iran and its proxies; Lebanon's Hezbollah, Yemen's Houthis and armed groups in Iraq.

Under the six-week first phase of the three-stage deal, Hamas will release 33 Israeli hostages, including all women (soldiers and civilians), children, and men over 50.

Israel will release all Palestinian women and children under 19 detained in Israeli jails by the end of the first phase. The total number of Palestinians released will depend on hostages released, and could be between 990 and 1,650 Palestinians, including men, women and children.

Hamas said in a statement on Friday that obstacles that arose in relation to the terms of the Gaza ceasefire agreement have been resolved.

In Gaza itself, Israeli warplanes kept up intense strikes, and the Civil Emergency Service said on Friday that at least 101 people, including 58 women and children, had been killed since the deal was announced on Wednesday.

Israel's acceptance of the deal will not be official until it is approved by the country's security cabinet and government.

In the early hours of Friday, Netanyahu's office said that Israel's security cabinet will meet to give final approval to the ceasefire accord, after the meeting was pushed back from Thursday raising concerns of delays.

A full cabinet meeting will be held later, but it was unclear exactly when.

Israel blamed Hamas for the last-minute hold-up, while Hamas on Thursday said it was committed to the deal, which is scheduled to take effect on Sunday.

ACCORD REACHED ON HOSTAGES

"Prime Minister Benjamin Netanyahu was informed by the negotiating team that agreements have been reached on a deal to release the hostages," his office said in a statement.

Underscoring the potential obstacles facing a final ceasefire, hardliners in Netanyahu's coalition have opposed the deal as a capitulation to Hamas, which runs Gaza, and National Security Minister Itamar Ben-Gvir threatened to resign if it is approved. However, he said he would not bring down the government.

His fellow hardliner, Finance Minister Bezalel Smotrich has also threatened to quit the government if it does not go back to war to defeat Hamas after the first six-week phase of the ceasefire was completed.

Nevertheless, a majority of ministers were expected to back the agreement.

In Gaza on Friday, the airstrikes continued. In the aftermath of one strike on tents housing displaced people, a boy picked through damaged items on the floor that was littered with canned food and coffee pots.

That attack killed two people and wounded seven others at an encampment close to Nasser Hospital in Khan Younis, according to medics.

Also in Khan Younis, mourners gathered around the body of a man killed in an Israeli strike as women hugged each other and cried.

"Life has become an unbearable hell," said resident Jomaa Abed al-Aal.

There was no immediate comment from the Israeli military on the latest strikes.

HOSTAGE FAMILIES WANT SWIFT ACTION

Israel says 98 hostages are still being held in Gaza. About half are believed to be alive. They include Israelis and non-Israelis. Of the total, 94 were seized in the Oct. 7, 2023, Hamas-led attack on Israel and four have been held in Gaza since 2014.

For the first time, Israeli authorities have officially informed hostage families of the names of the first 33 to be released but it remains unclear how many of those on the list are still alive.

A group representing families of Israeli hostages in Gaza urged Netanyahu to move forward quickly.

"For the 98 hostages, each night is another night of terrible nightmare. Do not delay their return even for one more night," the group said in a statement late on Thursday carried by Israeli media.

The ceasefire accord emerged on Wednesday after mediation by Qatar, Egypt and the U.S. As well as the release of hostages and Palestinian prisoners, the deal includes a gradual withdrawal of Israeli troops from Gaza.

It also paves the way for a surge in humanitarian aid for the coastal strip, where the majority of the population has been displaced, facing hunger, sickness and cold.

Israel launched its campaign in Gaza after Hamas-led gunmen burst into Israeli border-area communities on Oct. 7, 2023, killing 1,200 soldiers and civilians and abducting over 250 hostages, according to Israeli tallies.

(Reporting by James Mackenzie in Jerusalem, Nidal Al Mughrabi in Cairo and Hatem Khaled in Gaza; Writing Michael Georgy; Editing by Raju Gopalakrishnan and Sharon Singleton)