Prime Minister Ehud Olmert said on Saturday that Israel would not agree to any truce with Hamas without the release of an Israeli soldier who was captured in June 2006.
Egypt is trying to mediate a lasting truce between the two sides since a three-week war in Gaza ended in separate ceasefires on 18 January. Occasional exchanges of fire have occurred since then.
One of the conditions sought by Hamas is that all the crossings into the territory be opened, bringing an end to an Israeli blockade imposed when Hamas took over Gaza in 2007.
Hamas says that the release of the captured soldier must be negotiated as part of a separate prisoner exchange involving hundreds of people held in Israeli jails.
Israel insists the blockade will end only when Hamas releases the soldier.