Israel and Hamas broadly agree in principle that an exchange of Israeli hostages for Palestinian prisoners could take place during a monthlong cease-fire, but the framework plan is being held up by the two sides' differences over how to bring a permanent end to the Gaza war, three sources said.

Intense mediation efforts led by Qatar, Washington and Egypt in recent weeks have focused on a phased approach to release different categories of Israeli hostages — starting with civilians and ending with soldiers — in return for a break in hostilities, the release of Palestinian prisoners and more aid to Gaza.

The latest round of shuttle diplomacy started on Dec. 28 and has narrowed disagreements about the length of an initial cease-fire to around 30 days, after Hamas had first proposed a pause of several months, said one of the sources, an official briefed on the negotiations.