Israel on Tuesday said that human remains transferred by Hamas the previous day belonged to Ofir Tzarfati, an Israeli hostage whose body had already been recovered in a military operation around two years ago.

Prime Minister Benjamin Netanyahu's office said the finding "constitutes a clear violation of the agreement" between Israel and Hamas.

Under the first phase of the US-mediated cease-fire and hostage deal, Hamas is required to hand over 28 bodies from Gaza. The militant group has already released all living captives in exchange for hundreds of Palestinian prisoners.

"The prime minister will meet with the heads of the defense establishment, during which Israel’s steps in response to the violations will be discussed," Netanyahu's office said in a statement.

How was the body handed over by Hamas?

Israeli forces said they had received a coffin initially thought to contain the remains of another deceased hostage. The Israel Defense Forces confirmed late on Monday in a Telegram post that the remains had been brought into Israel.

The body was transferred to Israeli forces in Gaza via the Red Cross, Prime Minister Benjamin Netanyahu's office said in a separate statement.

"All of the hostages' families have been updated accordingly, and our hearts are with them in this difficult hour. The effort to return our hostages is ongoing and will not cease until the last hostage is returned," the statement had said.

The coffin was taken to the national forensic institute for identification and was to have been returned to the relevant hostage's family.

The news mean that Hamas has still only returned the remains of 15 of 28 deceased hostages, leaving 13 bodies still in Gaza.

Anger in Israel over slow return of deceased hostages

The latest exchange came as senior Israeli officials and an association representing the families of the October 7 hostages demanded that Hamas speed up the transfer of deceased hostages.

"Hamas knows exactly where every one of the deceased hostages is held. Two weeks have passed since the deadline set in the agreement for the return of all 48 hostages," the Hostages and Missing Families Forum said in a social media post on Monday.

The association urged the Israeli and US governments to pause further negotiations until the Palestinian militant group returned every hostage to Israel as agreed to under the terms of the US-brokered ceasefire deal between Israel and Hamas.

French news agency AFP cited Hamas spokesperson Hazem Qassem as saying claims the group knows the location of the remaining missing bodies were "false" as Israel's bombardment of Gaza during the more than two years of conflict had left locations unrecognizable.

"We affirm our commitment to completing the first phase of the ceasefire agreement to prevent the occupation from finding any pretexts," he said, according to AFP, referring to Palestinians' fears that Israel could renew military action despite the truce. 

"We are determined to hand over the bodies of the Israeli captives as soon as possible," he said.

Egypt, Red Cross help with search for hostage remains

Egypt sent a team of experts and heavy earth-moving equipment into Gaza on the weekend, with Israeli approval, to help with the recovery operation.

Israel confirmed that a team of Red Cross staff, Egyptian rescuers and a Hamas member were searching for bodies and had been allowed to cross the so-called Yellow Line into the area of Gaza controlled by Israeli forces.

Edited by: John Silk