NEW YORK — Nobel Peace Prize winner Jody Williams says a window of opportunity is now open to push U.N. officials to begin work on a new comprehensive treaty to ban nuclear weapons, but the opportunity shouldn't be squandered.

"I think we are at a moment of possibility, but I think if we don't seize that moment and push governments to do more now it will be lost," she said in an interview Friday on the sidelines of the nearly monthlong Nuclear Nonproliferation Treaty review conference that opened Monday.

The U.N. conference occurs only once every five years. World leaders weigh in on the performance of the treaty, the world's primary legal and political barrier against the proliferation of nuclear weapons, and debate strategies for improvement.