The remains of three people handed over by Hamas to the Red Cross this week do not belong to any of the hostages, Israel said on Saturday. This is the latest setback that could undermine a US-brokered ceasefire in the Israel-Hamas war. The handover followed Israel’s return on Friday of the bodies of 30 Palestinians to Gaza. That completed an exchange after militants earlier this week turned over remains of two hostages, a sign that the tense Israel-Hamas ceasefire agreement was edging forward.

Israeli Prime Minister Benjamin Netanyahu’s office on Saturday confirmed that the remains did not belong to any of the hostages, without giving further details. Hamas’ armed wing said in a subsequent statement that it had offered to hand over samples on Friday of unidentified bodies, but that Israel had refused to receive them and asked for the remains for examination. “We handed the bodies over to stop the claims of Israel,” the statement said. It was unclear who the remains belonged to.