The son of an Israeli hostage whose body remains in Gaza has told the BBC he is dealing with the realisation that “it’s not over and it’s going to be a longer battle”.

Rotem Cooper, whose father Amiram is among 24 hostages whose bodies were not returned to Israel on Monday, said the families were trying “to find the strength somehow to pick ourselves up… and continue the fight”.

He called on US President Donald Trump, Qatar, Egypt and other countries involved in peace deal negotiations “to show Hamas that this is not acceptable”.

A ceasefire and hostage release agreement signed by Israel and Hamas stated that the remaining hostages in Gaza would be returned by noon on Monday, with nearly 2,000 Palestinian prisoners and detainees held by Israel released in exchange.

While the 20 hostages still alive were released, a copy of the agreement published by Israeli media appeared to acknowledge that Hamas and other Palestinian factions may not be able to locate all of the bodies of the deceased hostages by the deadline.

Their families had pinned their hopes on their loved one returning on Monday, after two years in captivity.

“We hoped and expected that maybe 15 to 20 out of the 28 deceased hostages would be released, but that didn’t happen. Only four were announced,” Mr Cooper said.

He described the news as a “very big disappointment” for the families.

“It’s clear to us that they could have and should have released more and [that] they’re playing games.”

Mr Cooper’s parents were both kidnapped in the 7 October 2023 Hamas-led attacks on Israel, from their home in Kibbutz Nir Oz. His mother was released later that month while his father was killed in captivity.

The Israel Defense Forces (IDF) said it had been operating in the area at the time but did not confirm how he was killed, referring the BBC this week to a previous statement saying the circumstances were “under examination”. Hamas has claimed he was killed by an Israeli military strike.

The Hostages and Missing Families Forum, which represents the relatives of many of the hostages, has called for “a very serious response” from the Israeli government and mediators, for what is described as Hamas’s “violation of the agreement”.

It said further stages of the peace plan should not progress until all the remaining bodies had been returned.

Mr Cooper headed to the Re’im military base in southern Israel on Monday to see the return of the 20 living hostages.

In voicenotes sent over the course of the day, he described feeling “tremendous anticipation” and a “big relief” as he saw them return. But he said the thought of the bodies coming back to Israel was “heartbreaking”.

Speaking again the following day, after the news that the four bodies returned did not include Amiram’s, he described the experience as a “big rollercoaster”.

Mr Cooper said the return of his father’s body would allow him to have “some closure” and to “sleep better at night”.

“Everything has been on hold,” he said.

Ruby Chen, whose son Itay’s body remains in Gaza, said he had experienced a similar mix of emotions.

“We were overjoyed [on Monday] to see 20 hostages coming out and being reunited with their families, but we were very disappointed not to see more deceased hostages coming out,” he said in a video message shared with the BBC by the Hostages and Missing Families Forum.

“We request the Israeli government, the US and the mediators to continue the fight and put pressure on Hamas to adhere [to] and follow the agreement that was signed and bring back all the remaining 24 hostages in captivity,” Mr Chen added.

The Israeli military said on Tuesday that, following forensic tests, it had identified the four hostages whose bodies had been returned and had informed their families that their loved ones had been reburied.

It said they included Guy Iloz – who was shot at the Nova music festival and is believed to have died from the wounds – and Bipin Joshi, who it said was believed to have been “murdered in captivity during the first months of the war”.