The United States has sought to make Iran's alleged weapons plans the focus of the monthlong treaty review. But others want an equal emphasis on what they see as the softening commitment by Washington and other nuclear powers to eventually scrap their weapons, as the treaty requires.

Conference president Sergio de Queiroz Duarte, mediating the dispute, told reporters Friday many delegates ''keep their cards close to their chest until they have to take a decision. I expect in the next couple of days there will be movement.''

If not, and the sessions begin Monday with an incomplete agenda, ''it would be an unfortunate situation,'' the Brazilian diplomat said. He said he would steer the conference to ''noncontentious points'' while backroom talks continue.

But the contentious points are piling up:

l North Korea's withdrawal from the treaty and declaration it has built nuclear weapons.

l Iran's secretive, years-long program to enrich uranium, a potential step toward a bomb.

l U.S. interest in developing new nuclear arms, and its rejection of some arms-control pacts.

l The threat of nuclear terrorism.

Because of such developments, ''parties are concerned about the erosion of confidence in the treaty,'' Duarte said.

The Nuclear Nonproliferation Treaty, which is formally reviewed every five years, is essentially a global bargain: States without nuclear weapons pledge not to pursue them, and five with the weapons - the United States, Russia, Britain, France and China - pledge to move toward eliminating them.

A third keystone of the 188-nation treaty is a guarantee that countries without atomic bombs will have access to nuclear technology for peaceful purposes. Iran says its uranium enrichment is meant solely for civilian energy.

Although India, Pakistan and Israel, treaty nonmembers, have developed atomic weapons, the treaty is credited with having prevented a wider nuclear free-for-all. But the treaty's flaws, such as North Korea's 2003 withdrawal without sanction, have become more apparent in recent years.

Duarte indicated the conference may not focus heavily on North Korea itself, so that on-and-off six-party negotiations have time to draw the North Koreans back into the treaty.

But he said treaty members might discuss the subject of withdrawal; some propose changes to subject future North Koreas to possible penalties.