Israel says a coffin handed over by Hamas on Monday did not contain the body of another deceased hostage but more of the remains of another person held captive whose body had been previously returned.

Forensic tests showed the remains belonged to Ofir Tzarfati, whose body was recovered by Israeli forces in late 2023, and not to any of the 13 deceased hostages still in Gaza, Israeli Prime Minister Benjamin Netanyahu’s office said.

It accused Hamas of a “clear violation” of the two-week-old Gaza ceasefire deal and said Netanyahu would discuss “steps in response”.

Hamas denied delaying the return of the hostages and claimed Israel was seeking “false pretexts” in preparation for “aggressive steps”.

The Palestinian group’s military wing also announced separately that it would hand over the body of a deceased hostage to the Red Cross on Tuesday evening.

Hamas insists it is complying with the ceasefire agreement brokered by the US, Egypt, Qatar and Turkey and is doing its best to find remains under the rubble left by two years of war.

However, Israeli officials insist that it knows the locations of all the hostages.

On Monday evening, Hamas announced that it would hand over to the Red Cross the body of an Israeli hostage which had been recovered earlier in the day.

A few hours later, the Israel Defense Forces (IDF) confirmed that its troops in Gaza had received a coffin and taken it to the National Institute for Forensic Medicine in Tel Aviv for identification procedures.

But the Israeli prime minister’s office said it was found that “remains belonging to fallen hostage Ofir Tzarfati – of blessed memory, who was returned from the Gaza Strip in a military operation about two years ago – were returned”.

“This constitutes a clear violation of the agreement by the Hamas terrorist organisation,” it added. “Prime Minister Netanyahu will hold a security discussion with the heads of the security establishment to discuss Israel’s steps in response to the violations.”

Tzarfati, a 27-year-old Israeli-French dual national, was shot and wounded while being abducted by Hamas gunmen at the Nova music festival during the 7 October 2023 attack on southern Israel, which triggered the Gaza war.

At the start of December 2023, the IDF announced that his body had been found by its forces in Gaza and brought back to Israel.

In March 2024, additional remains belonging to him were returned for burial.

“We went to sleep last night with anticipation and hope that another family would close an agonising two-year circle and bring their loved one home for burial. But once again, deception has been inflicted upon our family as we try to heal,” Tzarfati’s family said in a statement.

They added: “This morning we were shown video footage of our beloved son’s remains being removed, buried, and handed over to the Red Cross – an abhorrent manipulation designed to sabotage the deal and abandon the effort to bring all the hostages home.”

Later, the IDF released footage from a drone filmed that it said showed Hamas operatives “removing body remains from a structure that had been prepared in advance and burying them nearby” on Monday.

“Shortly afterwards,” it added, the operatives “summoned representatives of the Red Cross and staged a false display of discovering a deceased hostage’s body.”

Hamas issued a statement rejecting what it called Israel’s “baseless allegations”.

It accused Israel of preventing the entry into Gaza of the heavy machinery needed to accelerate and complete the search for the hostages’ bodies.

“[Israel] is seeking to fabricate false pretexts in preparation for taking new aggressive steps against our people, in a flagrant violation of the ceasefire agreement,” it added.

There was no immediate comment from the Red Cross.

The Hostages and Missing Families Forum in Israel, which represents the relatives of many hostages, demanded an urgent meeting with the prime minister to discuss responses to what it called Hamas’s “despicable actions”.

“Hamas’s repeated violations and the IDF’s documentation prove what we have known and stated clearly and unequivocally: Hamas knows the location of the hostages and continues to act with contempt, deceiving the United States and mediators while dishonouring our loved ones,” it said.

“The Israeli government cannot and must not ignore this, and must act decisively against these violations.”

Israeli government spokeswoman Shosh Bedrosian told a briefing that Hamas would now face “serious repercussions” failure to return all the deceased hostages’ bodies within 72 hours of the ceasefire taking effect on 10 October, as it had agreed.

“There is a meeting taking place, the prime minister is holding, and in terms of consequences for Hamas, nothing is off the table right now, but all of this is in full co-ordination with the United States,” she said.

It is understood that Israeli officials are discussing with the Trump administration various responses to Hamas’s failure to return all the deceased hostages’ bodies within 72 hours of the ceasefire taking effect on 10 October.

One being considered is said to be expanding the area of Gaza under IDF control, which is demarcated by the so-called “Yellow Line”.

Public broadcaster Kan News said the first step taken by Israel would be to stop allowing Hamas members and Red Cross representatives to visit IDF-controlled territory to help an Egyptian team with earth-moving equipment search for the remaining dead hostages.

The Israeli government had confirmed on Monday that such visits were being permitted “under close IDF supervision”.

All 20 living Israeli hostages were released soon after the ceasefire took effect on 10 October in exchange for 250 Palestinian prisoners and 1,718 detainees from Gaza.

Israel has also handed over the bodies of 195 Palestinians in exchange for the bodies of the 13 Israeli hostages previously returned by Hamas, along with those of two foreign hostages – one of them Thai and the other Nepalese.

Eleven of the dead hostages still in Gaza are Israelis, one is Tanzanian, and one is Thai.

On Saturday, Hamas’s chief negotiator Khalil al-Hayya said the group was facing challenges because Israeli forces had “altered the terrain of Gaza”. He also said that “some of those who buried the bodies have been martyred or no longer remember where they buried them”.

All but one of the dead hostages still in Gaza were among the 251 people abducted during the Hamas-led attack on southern Israel on 7 October 2023, during which about 1,200 other people were killed.

Israel responded by launching a military campaign in Gaza, during which more than 68,500 people have been killed, according to the territory’s Hamas-run health ministry.