A temporary truce and the release of dozens of captives taken by Palestinian armed group Hamas in its assault on Israel on October 7 will not start before Friday, Tel Aviv has said, as Israeli forces continued to bombard the besieged enclave of Gaza.

The release is part of a temporary truce, initially expected to last four days, that was agreed by Israel and Hamas on Wednesday and also includes the deployment of desperately needed humanitarian aid to Gaza.

The captives are supposed to be exchanged for a number of Palestinians held in Israeli jails.

“The negotiations on the release of our hostages are advancing and continuing constantly,” Israeli National Security Adviser Tzachi Hanegbi said in a statement released by the prime minister’s office.

“The start of the release will take place according to the original agreement between the sides, and not before Friday,” it said.

Israel’s public broadcaster Kan, quoting an unidentified Israeli official, reported there was a 24-hour delay because the agreement had not been signed by Hamas and Qatar, which was the key mediator in the deal. The official said they were optimistic the agreement would be carried out when it was signed.

“No one said there would be a release tomorrow except the media … We had to make it clear that no release is planned before Friday, because of the uncertainty that hostages’ families are facing,” Kan quoted an unnamed source in Israeli Prime Minister Benjamin Netanyahu’s office as saying.

Other Israeli media published similar reports, quoting anonymous officials, that the pause in fighting with Hamas would not start before Friday.

More than 14,500 people have been killed in Gaza since Israel began its attacks on the territory in response to Hamas’s assault on Israel that left at least 1,200 people dead.

About 240 people were taken by Hamas fighters, and only four have been released so far.

There were about 5,200 Palestinians in Israeli prisons prior to October 7, although that number has more than doubled in the weeks since, according to Palestinian authorities.

Amid the apparent delay to the truce agreement, Israeli aircraft and artillery struck Gaza’s southern city of Khan Younis in at least two waves early on Thursday.

In Israel, sirens warning of incoming rocket fire from Gaza blared in communities near the border with the enclave, the military said. There were no reports of damage or injuries.

Tensions also rose on Israel’s northern border early on Thursday after the Iran-backed Hezbollah group said five of its fighters, including the son of a senior lawmaker, had been killed.

In the Red Sea, meanwhile, US Central Command said the USS Thomas Hudner had “shot down multiple one-way attack drones launched from Houthi controlled areas in Yemen”, referencing another Iran-backed group.

‘I want everybody back’

The delay caused frustration among families on both sides.

Under the terms of the agreement, 50 Hamas captives are due to be released, with a minimum of 10 being freed each day.

“We don’t know who will get out because Hamas will release the names every evening of those who will get out the next day,” said Gilad Korngold, who was still awaiting word of relatives. Seven of his family members, including his three-year-old granddaughter, were kidnapped by Hamas.

“I want everybody back. But I think – and it’s a very tough decision – but I think the children and women must be [first]. They are most fragile. You know, they need to get out.”

Netanyahu’s office has said the truce could be extended as long as an additional 10 hostages were freed each day.

On Israel’s list of 300 eligible Palestinian prisoners of 123 children and 33 women is Shorouq Dwayyat, who is serving a 16-year sentence for attempted murder in a 2015 knife attack. Campaigners say she is one of many Palestinians to have been unjustly tried and sentenced on unfair or fabricated charges.

“I had hoped that she would come out in a deal,” her mother, Sameera Dwayyat, said but added that her relief was tempered by “great pain in my heart” over the dead children in Gaza.

The US also hoped that aid would begin reaching Gaza in large volumes in the coming days, White House national security spokesperson John Kirby said.

Hamas said the initial 50 captives would be released in exchange for 150 Palestinian women and children imprisoned in Israel. Hundreds of trucks of humanitarian, medical and fuel supplies would enter Gaza, while Israel would halt all air sorties over southern Gaza and maintain a daily six-hour daytime no-fly window in the north, it added.

The truce agreement, the first in a nearly seven-week-long war, was reached after mediation by Qatar and seen by governments around the world as potentially easing the suffering in the Gaza Strip, which is home to more than two million people.

In a statement shared by US media outlets, National Security Council spokesperson Adrienne Watson stressed the deal “was agreed and remains agreed”.

“The parties are working out final logistical details, particularly for the first day of implementation,” CBS News and CNN reported Watson as saying.

“It is our view that nothing should be left to chance as the hostages begin coming home. Our primary objective is to ensure that they are brought home safely. That is on track, and we are hopeful that implementation will begin on Friday morning.”