Prime Minister Ariel Sharon (search) on Sunday said he opposes any further releases of Palestinian prisoners until the Palestinians (search) take tougher action against militant groups.

Sharon made the announcement at a Cabinet meeting, hours before Israeli and Palestinian negotiators were to meet to discuss the releases. Under a February cease-fire, Israel agreed to release 900 Palestinian prisoners. It has so far released 500.

Sharon said he would instruct his negotiators to make clear to the Palestinians that no more releases can take place until the Palestinians clamp down on militants.