Israel said that three bodies it received from Gaza last night were not hostages held in the Palestinian territory, as a Hamas security source reported fresh strikes in the south.
A fragile truce has been holding in Gaza since 10 October, based on a US-brokered deal centred on the return of all Israeli hostages, both living and dead.
Israel's military said that a forensic analysis revealed that three bodies it received via the Red Cross yesterday were not those of any of the deceased captives still to be handed over as part of the ceasefire deal.
Hamas's armed wing said this morning that it had handed over bodies it had not positively identified, alleging Israel had declined its offer to provide samples for testing and "demanded the bodies for examination".
"We handed them over to pre-empt any enemy claims," the Ezzedine Al-Qassam Brigades said.
After the start of the truce, Hamas returned the 20 surviving hostages still in its custody and began the process of returning the remains of the dead.
Of the 17 bodies returned since the start of the ceasefire, 15 were Israelis, one was Thai and one was Nepalese.
Hamas has also returned another unidentified body that had not been listed among the 28 missing, as well as the partial remains of a deceased Israeli hostage who had already been recovered early in the war.
That incident drew outrage in Israel, which said the group had violated the agreement by returning the partial remains rather than the body of another hostage.
Israel has accused Hamas of not returning the dead hostages quickly enough, but the Palestinian group says it will take time to locate remains buried in Gaza's ruins.
In its statement, the Al-Qassam Brigades called on mediators and the Red Cross to provide the "necessary equipment and personnel to work on recovering all the bodies simultaneously".
Hamas and Israel, meanwhile, have traded accusations of breaking the ceasefire.
A Hamas security source SAID that Israel had carried out several air strikes in the south at dawn, and that "warships opened fire toward the shores of Khan Younis".
Earlier in the week, the Israeli military launched its deadliest night of bombing since the truce after one of its soldiers was killed in south Gaza, with the territory's civil defence agency reporting more than 100 people killed.
Hamas denied it had anything to do with the attack, and Israel later said it had begun "renewed enforcement of the ceasefire".
The implementation of the later stages of US President Donald Trump's ceasefire plan has yet to be agreed, particularly as it concerns disarming Hamas, establishing a transitional authority and deploying an international stabilisation force.
The force is expected to be drawn from a coalition of mainly Arab and Muslim nations, and would train and support vetted Palestinian police, with backing from Egypt and Jordan, as well as secure border areas and prevent weapons smuggling.
The foreign ministers of Jordan and Germany insisted at a conference in Bahrain that the international force have the blessing of the United Nations.
"We all agree that in order for that stabilisation force to be able to be effective in getting the job done, it has to have a Security Council mandate," Jordanian Foreign Minister Ayman Safadi said.
His German counterpart Johann Wadephul said such a mandate would be of the "utmost importance to those countries who might be willing to send troops to Gaza, and for the Palestinians".
