Israel has said it is extremely concerned about their condition but has not confirmed their deaths.

Hamas leader Khalil al-Hayya, in prerecorded remarks on Tuesday, did not elaborate beyond saying that the “Bibas family” would be included in the handover of four bodies.

The six to be released on Saturday are the last living hostages to be freed under the first phase of the ceasefire in Gaza. Three hostages had been expected to be freed on Saturday. It was not clear why Hamas changed the plan.

The warring sides have yet to negotiate the second and more difficult phase, in which Hamas would release dozens more hostages in exchange for a lasting ceasefire and an Israeli withdrawal.

The hostage releases have come in exchange for hundreds of Palestinian prisoners held by Israel.

The ceasefire that began in mid-January has paused the deadliest fighting ever between Israel and Hamas, surged aid into devastated Gaza and allowed hundreds of thousands of Palestinians to return to their homes as Israeli forces withdrew from much of the territory.