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One of the four bodies handed over by Hamas was not that of Shiri Bibas, despite claims by the militant group, Israel said on Friday after hostage remains were transferred from Gaza in tense scenes.
The body purported to be Ms Bibas does not match any kidnapped person, Israeli authorities added. Hamas said it would "examine these claims with complete seriousness".
Hamas on Thursday said it was returning four hostage bodies including those of Ms Bibas and her two young sons, Ariel and Kfir, as part of its ceasefire agreement with Israel. The Israeli military said it carried out tests to identify the bodies and determine the causes of death.
The news added to rage in Israel where government ministers were already urging a return to fighting following the reception of the four bodies on Thursday. There are fears that Saturday's scheduled release of six living hostages could now be at risk.
"During the identification process, it was determined that the additional body received is not that of Shiri Bibas, and no match was found for any other hostage. This is an anonymous, unidentified body," the military said on X. "This is a very serious violation by Hamas."
Israeli Prime Minister Benjamin Netanyahu vowed Hamas will pay the full price for a “cruel and evil violation of the agreement” in a video address released on Friday morning.
Mr Netanyahu said the group demonstrated “unspeakable cynicism” and that “the cruelty of the Hamas monsters knows no bounds”.
Hamas on Friday afternoon said it was "surprised by the commotion caused by the [Israeli] occupation" and that it "rejects the threats issued by Benjamin Netanyahu as part of his attempts to improve his image in front of the Zionist community".
It added that there was the "possibility of a mistake or interference with the corpses, [which] may be the result of the occupation targeting and shelling the place where the family was with other Palestinians".
Hamas spokesman Basem Naim released a separate statement saying, "In the midst of the Zionist genocide that led to the killing of thousands of innocent Palestinian children and women, and the destruction of the Gaza Strip and all aspects of life in it, some unfortunate mistakes may occur.
"We would like to remind the world that we received thousands of bodies from the Zionist enemy in blue bags without any identification on them and without any respect for their humanity, and we did not hear any condemnation of these crimes from international officials and the official western media did not care about Palestinian human rights."
The International Committee of the Red Cross (ICRC) on Friday denied online reports, accompanied by images of lines of blue body bags holding Palestinian corpses, that it was involved in the transfer of remains held in Israel to Gaza.
“The ICRC stands ready to facilitate the transfer of the deceased, including transmission of information, as a part of its role as a neutral humanitarian intermediary,” the statement read.
“It is ready to play this role if and when the parties to the conflict reach an agreement beforehand, in consultation and consistent with ICRC’s modalities to ensure the safeguarding of human dignity.”
The Israeli military's Arabic-language spokesman Lt Col Avichay Adraee said on Telegram that Israel had identified the remains of the Bibas boys, and he accused Palestinian "terrorists" of killing them. Israel usually refers to militants in Gaza and the occupied West Bank as terrorists.
Hamas has long maintained an Israeli air strike killed Shiri Bibas and her sons early in the war while they were being held in Gaza.
Earlier, Mr Netanyahu's office said hostage Oded Lifshitz, whose body was also handed over by militants in Gaza on Thursday, had been murdered in captivity by the Palestinian Islamic Jihad group.
The repatriations were part of the ceasefire deal between Israel and Hamas that took effect on January 19. The agreement has so far led to the release of 19 living hostages in exchange for more than 1,100 Palestinian prisoners.
Flag-waving Israelis lined the route of a convoy carrying the bodies travelling from southern Israel to Tel Aviv.
The Bibas family have become symbols of the hostage crisis in Israel. During the Hamas attack on southern Israel in October 2023 that sparked the Gaza war, Hamas filmed and later broadcast footage showing the family's abduction from their home near the Gaza border.
Ariel was aged four at the time, while Kfir was the youngest hostage at just nine months old. Yarden Bibas, the boys' father and Shiri's husband, was abducted separately and released in a previous hostage-prisoner swap on February 1.
Hamas said in a statement that it had done everything in its power "to protect the prisoners and preserve their lives".
Palestinian militant groups on Thursday held an event to hand over the bodies in the southern Gaza city of Khan Younis, displaying four black coffins with photos of the dead.
Mr Netanyahu said in a video message after the handover that "we are all enraged at the monsters of Hamas", vowing to destroy the group.
Hamas on Friday released a list of six more live hostages who would be traded for Palestinian prisoners held in Israel on Saturday.
Elijah Maimon Yitzhak Cohen, Omar Shem Tov, Omer Finkert and Tal Shoham were all taken hostage during the October 7 attacks. The remaining two, Avera Mengistu and Hisham Al Sayed, were taken captive almost a decade ago after crossing into Gaza. Both are said to suffer from mental health issues.
Mr Netanyahu's office confirmed receiving the list, but did not give the names of the hostages.
Hours after Thursday's transfer, police reported a "suspected terror attack" in two Israeli suburbs outside Tel Aviv, saying three bombs had exploded on or around buses, although no casualties were reported. Local media said the blasts had occurred on buses in depots that were empty.
Large numbers of police were deployed to search for suspects, a police statement said. There was no immediate claim of responsibility for the explosions.
In response, Mr Netanyahu instructed the military to carry out an "intensive" operation in the occupied West Bank, describing the explosions as an attempted mass attack. The military said it would intensify counter-terrorism operations in the West Bank and that it had blocked entry points in certain areas, without specifying where.
