Khalil al-Hayya, Hamas’s chief negotiator, said in a speech on Tuesday that militants intend to hand over the remains of four Israeli hostages to Israel on Thursday in exchange for the release of Palestinian prisoners.

Mr. Hayya said members of the Bibas family would be among the four bodies handed over to Israel on Thursday. The three remaining members of the Bibas family in Gaza include Shiri Bibas and her two children.

Israeli officials said earlier on Tuesday that they expected the remains of Israeli hostages to be returned to Israel on Thursday, though they did not specify that members of the Bibas family would be among them.

Hamas will also increase the number of living hostages scheduled to be released on Saturday to six from three, Mr. al-Hayya said.