With momentum toward international adoption of a nuclear test ban treaty stalled, representatives of more than 100 countries urged holdouts to ratify the document Friday.
Leaders convened at the United Nations General Assembly to mark fifteen years since the treaty was negotiated and to press remaining countries to bring it into force.
The Comprehensive Nuclear Test Ban Treaty has been signed by 182 countries and ratified by 155 of them. But it needs to be ratified by all 44 states identified as nuclear technology holders to enter into force.
Nine have not yet done so _ China, North Korea, Egypt, India, Indonesia, Iran, Israel, Pakistan and the United States.
U.N. chief Ban Ki-moon told the delegates the ban was "an indispensable stepping stone to a nuclear-weapon-free world."
He joked that he was uniquely qualified to make the case.
"My name is spelled Ban," he said. "Therefore my name has a very clear, firm determination - nuclear test ban. I will ban this nuclear test."
Ban and other officials urged holdouts to ratify quickly.
Proponents of the treaty hoped that U.S. ratification would pressure the remaining holdouts. But despite support from U.S. President Barack Obama, the treaty has run into strong opposition from Republicans in the U.S. Senate and is unlikely to be considered before elections in 2012.
Swedish Foreign Minister Foreign Minister Carl Bildt, who co-chaired Friday's conference, said he hoped that other countries would move without the United States.
"We are hopeful that at one point the U.S. will be ready to ratify," he told reporters. "Clearly the U.S. political agenda has moved in the other direction."
(This version CORRECTS Changes dateline to correct to 'United Nations' sted 'Washington,' fixes category code. Updates with background, quotes. For global distribution.)