Hamas said on Tuesday that no further progress can be made on the ceasefire agreement with Israel without the release of Palestinians from prison. The announcement casts doubt on the future of the deal.

The two sides have been working under the first phase of an agreement that paused the fighting in the Gaza Strip. It calls for Israel to free more than 600 Palestinian prisoners in exchange for the release of Israeli hostages. The first phase is due to expire on Saturday.

However, Israeli Prime Minister Benjamin Netanyahu said his side will delay the release of the prisoners because Hamas is in violation of the agreement for what he calls "humiliating" ceremonies that accompany the freeing of the hostages.

Hamas said that decision puts the agreement "at risk of collapse" and could lead to a "resumption of war." It said it will not return the bodies of four Israeli hostages that it had previously agreed to hand over.

Talks on the second phase, including a permanent end to the fighting, have reportedly made little progress. The US Special Envoy to the Middle East, Steve Witkoff, is scheduled to visit Israel and other countries to seek the extension of the first phase.