US President Donald Trump has ordered all Hamas hostages to be freed by Saturday, threatening “all hell is going to break out” otherwise.

Trump said that after the freeing of three visibly emaciated hostages it was time for Israel to demand the release of all hostages by noon on Saturday, or restart the war.

“As far as I’m concerned, if all of the hostages aren’t returned by Saturday at 12 o’clock — I think it’s an appropriate time — I would say cancel it and all bets are off and let hell break out,” he said at the White House on Tuesday (AEDT), without specifying the exact time zone.

“If they’re not here, all hell is going to break out,” Trump said. He added of the ceasefire, “Cancel it, and all bets are off.”

Trump said the final decision would be up to Israel, saying, “I’m speaking for myself. Israel can override it.”

But asked if the US would join in a response to Hamas if hostages weren’t freed, Trump added, “Hamas will find out what I mean.”

He said he thought many of the remaining hostages were already dead.

So far, 16 of the 33 hostages to be released in the first 42-day phase of the ceasefire deal have come home, as well as five Thai hostages who were returned in an unscheduled release.

Israeli public opinion was shocked by the emaciated appearance of Ohad Ben Ami, Eli Sharabi and Or Levy when they were released last Saturday.

Another exchange of Israeli hostages for Palestinian prisoners had been scheduled for Saturday.

In exchange, Israel has released hundreds of prisoners and detainees, ranging from prisoners serving life sentences for deadly attacks to Palestinians detained during the war and held without charge.

Earlier, Abu Ubaida, a spokesman for Hamas’ military wing, said that since the ceasefire came into effect on January 19, Israel had delayed allowing displaced Palestinians from returning to the northern part of the Gaza Strip, targeted Gazans with military shelling and gunfire and had stopped relief materials entering the territory.

The ceasefire has largely held over the past three weeks although there have been some incidents where Palestinians have been killed by Israeli gunfire.

The flow of humanitarian aid into the Gaza Strip has increased since the ceasefire, aid agencies say.

Ubaida said Hamas would release no more hostages until Israel “complies and compensates for the past weeks”.

Hamas has also accused Israel of dragging its feet on allowing aid into the enclave, one of the conditions of the first phase of the agreement, a charge Israel has rejected as untrue.

In turn, Israel has accused Hamas of not respecting the order in which the hostages were to be released and of orchestrating abusive public displays before large crowds when they have been handed over to the Red Cross.

Earlier, the office of Israeli Prime Minister Benjamin Netanyahu had said an Israeli delegation had returned from ceasefire talks in Qatar, amid already growing doubts over the Egyptian and Qatari-brokered process to end the war.

A Palestinian official close to the discussions said progress was being held up by mistrust between the two sides.

Trump’s statements that Palestinians should be moved out of the Gaza Strip, leaving the coastal enclave to be developed as a waterfront real estate project under US control have also up-ended expectations for the postwar future.

On Monday, Fox News released an excerpt of an interview with Trump.

Asked about the plan and whether Palestinians would have the right of return, he answered: “No, they wouldn’t, because they’re going to have much better housing.”

“I’m talking about building a permanent place for them because if they have to return now, it’ll be years before you could ever – it’s not habitable.”

Trump said he thought he could make a deal with Egypt and Jordan to take Gazans.

Netanyahu endorsed Trump’s comments when he returned from a visit to Washington DC at the weekend, causing irritation in Egypt, where security sources said Israel was “putting up roadblocks” to the smooth progress of the ceasefire deal, including delays to withdrawal of its troops and continuing aerial surveillance.

-with AAP