Hamas hands over remains said to be those of Shari, Ariel and Kfir ...

Hamas has returned the bodies of four hostages to Israel, on what Israeli Prime Minister Benjamin Netanyahu earlier labelled a "wrenching day, a day of grief" for Israelis.

WARNING: This story contains details some readers may find distressing.

The remains are said to include those of Shiri Bibas and her two young children, Ariel and Kfir, who were abducted from Kibbutz Nir Oz in southern Israel during the October 7, 2023, terror attacks.

Kfir was just nine months old when he was taken hostage with the rest of his family.

The fourth body is reported to be that of Israeli great-grandfather and peace activist Oded Lifschitz, who was 83 when he was also taken from the same community.

Before the handover, which took place in Khan Younis and was facilitated by the Red Cross, Hamas militants displayed the four black coffins containing the remains on a stage in front of onlookers and the media.

The stage was draped with messages blaming Israeli Prime Minister Benjamin Netanyahu and the Israel Defense Forces (IDF) for the hostages' deaths.

Hamas has previously said Ms Bibas and her sons were killed as Israel launched its bombardment of Gaza in November 2023, while Mr Lifshitz was killed in a separate Israeli strike.

Israel has never officially confirmed the four hostages' deaths.

Mr Netanyahu's office issued a statement after the coffins were handed over by the Red Cross to the IDF and the Israeli security service, Shin Bet, elsewhere in Gaza.

"After the identification process, an official announcement will be made to the families," the statement said.

"The public is asked to respect the families' privacy and refrain from spreading rumours and information that is not official and well-founded."

The Israel Defense Forces (IDF) later confirmed about midday Thursday, local time, that the remains had arrived in Israel and were to undergo identification in Tel Aviv.

"A short while ago, IDF and ISA forces brought the coffins of the four deceased hostages over the border into Israel, and they are being taken to the National Institute of Forensic Medicine to undergo an identification procedure," it said in a statement posted to X.

Israelis lined the highways as the convoy made its way north to Tel Aviv.

The remains of Shiri Bibas and her two children Ariel and Kfir, and the fourth hostage Oded Lifschitz, will now go through a formal identification process.

Authorities say the process could take some time, depending on the condition of the bodies.

It's the first time Hamas has released bodies of dead hostages during the current six-week ceasefire.