JERUSALEM  Israel’s security cabinet voted Wednesday to make the opening of Israel’s border crossings with Gaza, a central Hamas demand for any long-term cease-fire arrangement, conditional on the release of an Israeli soldier held by Hamas.

The cabinet decision, widely seen as a hardening of the Israeli stance, seemed to dim the prospects for a quick conclusion to the Egyptian-brokered talks for a consolidated truce.

But the unanimous vote merely formalized the position that was being articulated with increasing clarity in recent days by the Israeli prime minister, Ehud Olmert, and seemed more focused on expediting a prisoner exchange deal with Hamas for the soldier’s return.

Hamas, the militant Islamic group that controls Gaza, is demanding the release of as many as 1,400 Palestinian security prisoners in Israeli jails in return for the captive soldier, Cpl. Gilad Shalit. He was seized in a cross-border raid and taken into Gaza by Hamas and other militant groups in June 2006.