Prime Minister Benjamin Netanyahu has ordered the Israeli military not to begin a ceasefire in Gaza, scheduled to begin at 8:30 a.m. (0630 GMT), until Hamas announces it, his office said List of prisoners to be released.

"The prime minister instructed the Israel Defense Forces that the ceasefire is scheduled to take effect at 8:30 a.m. and will not begin until Israel receives a list of released abductees promised by Hamas," his office said in a statement. Sunday.

In a statement shortly afterwards, Hamas blamed "technical reasons" for the delay in handing over the names. It said it was committed to abiding by the ceasefire announced last week.

Al Jazeera's Stephanie Decker, reporting from Amman, said both Hamas and Israel are facing "enormous international pressure" and it would be "difficult" to see the ceasefire, especially the first phase, not continuing conduct.

"Is it possible that there are some delays at the moment? I'm pretty sure that if it's true that the names haven't been handed over yet, Qatar will put a lot of pressure on Hamas," she said.

"But Hamas reaffirms its commitment to the ceasefire and will then hand over the names as soon as possible."

The latest development came hours after Netanyahu said Israel reserved the right to resume the war in Gaza and would receive U.S. support if the second phase of a ceasefire did not come to fruition.

The first phase of the 42-day ceasefire is expected to result in the return of a total of 33 hostages from Gaza and the release of hundreds of Palestinian prisoners and detainees.

Israeli forces should withdraw to the buffer zone inside Gaza and the many displaced Palestinians should be able to return to their homes. Humanitarian aid should also surge in affected areas.

It was only the second cease-fire in the war, longer and more consequential than the week-long truce more than a year ago and threatening to end the fighting for good.

Negotiations on a more difficult second phase of the ceasefire are due to begin in two weeks. Major questions remain, including whether the war will resume after the six-week first phase and how the remaining nearly 100 hostages in Gaza will be released.

Israel's cabinet approved the ceasefire early Saturday in a rare meeting held during the Jewish Sabbath, more than two days after mediators announced it.

The warring sides are under pressure from the outgoing Biden administration and President-elect Donald Trump to reach a deal before the U.S. presidential inauguration on Monday.