Israel's powerful security cabinet was to meet on Wednesday to decide whether to back Prime Minister Ehud Olmert's stance that a captive soldier be released as part of a Gaza truce deal.
A vote to support the position of the outgoing premier risks further complicating Egyptian efforts to broker a lasting truce around the enclave as its Hamas rulers have already rejected the condition.
Olmert first made the demand that Gilad Shalit, a soldier seized by Gaza militants in June 2006, be released as part of a truce deal at the weekend.
"We want first to resolve the Shalit issue and then will look into the reopening of crossings and the rehabilitation of the Gaza Strip," he said on Tuesday, repeating his position.
His demand was swiftly rejected by Hamas's exiled leader Khaled Meshaal, who again accused Israel of backtracking on the terms of a proposed long-term truce by linking the lifting of the blockade to the soldier's release.
"Israel is responsible for blocking Egypt's efforts to broker a truce by adding a new condition at the last minute," Meshaal said after Damascus talks with Arab League chief Amr Mussa.
"A truce can come about only in exchange for a lifting of the blockade and the reopening of the crossing points. It is unacceptable to combine the truce issue with the question of Israeli prisoner Gilad Shalit," Meshaal said.
Egypt, which has been acting as intermediary in separate negotiations for a Gaza truce and for an exchange of Palestinian prisoners in Israeli jails for Shalit, has also said that the two issues should be kept separate.
"Egypt will not change its position on the truce -- the matter of the Israeli soldier Gilad Shalit is a separate issue which can in no way be linked to the truce negotiations," the state-owned Egyptian daily Al-Ahram quoted President Hosni Mubarak as saying.
Shalit was captured in a deadly cross-border raid from Gaza in June 2006.
His family on Tuesday evening issued a statement demanding that his release should be "the first condition in any accord on a truce" with Hamas.
"The chance which currently presents itself must not be missed as it was in previous agreements," Israeli army radio quoted the statement as saying in reference to a six months' truce in Gaza agreed between Israel and Hamas in June last year.
Egypt has been acting as a go-between in efforts to consolidate the separate ceasefires that ended Israel's deadly 22-day Gaza offensive on January 18. The war killed more than 1,300 Palestinians and 13 Israelis.