Hamas said it is prepared to release American-Israeli soldier Edan Alexander and the bodies of four dual nationals held hostage in Gaza.

Hamas says it will only release an American-Israeli and the bodies of four other hostages if Israel implements the existing ceasefire agreement in the Gaza Strip, calling it an "exceptional deal" aimed at getting the truce back on track.

The announcement comes as talks continue in Doha to try to broker the second stage of the Israel-Hamas ceasefire, the first phase of which ended two weeks ago.

Israel said it sent ground troops back into the center and south of the Gaza Strip, expanding a military operation that began with a wave of airstrikes a day earlier that Palestinian authorities said killed hundreds of people.