``We will not attend the conference,'' said the official, who asked not to be named. He did not elaborate on the reasons.

The aim of the conference is to review progress toward ratification of the Comprehensive Test Ban Treaty (CTBT), which would ban all nuclear blasts, whether in the atmosphere, in space or underground.

The Pentagon, hoping to hasten the treaty's death, has been pressing the administration for months to sit out the meeting, which initially was scheduled for late September but postponed after the Sept. 11 suicide airliner attacks on New York and Washington.

The CTBT has not yet entered into force because it has not garnered the necessary ratifications. It expands on a 1963 treaty barring tests in the atmosphere and a 1974 treaty setting limits on underground explosions.

The George W. Bush administration worries that without testing, it cannot ensure the safety and reliability of U.S. nuclear arms. Critics say simulated testing conducted via computers and other technology is sufficient.

U.S. officials insist Bush remains deeply concerned about nuclear proliferation and expects to continue abiding by a testing moratorium put in place by his father in 1992.

But critics say a boycott of the U.N. conference will be a powerful message to allies strongly backing the CTBT that Washington wanted to go it alone on nuclear arms control.

WASHINGTON WAS STRONG BACKER

``This will not be the last word. But it's a sad commentary on the Bush administration's approach to post-September 11 weapons-of-mass-destruction challenges,'' said Daryl Kimball, executive director of the Washington-based Arms Control Association.

``Just as we cannot fight global terror alone, we cannot alone fight the proliferation of nuclear, chemical and biological weapons,'' he told Reuters.

Some 79 other nations have signed up to deliver speeches at the three-day CTBT event, but organizers said earlier on Friday they had not yet heard from Washington.

The United States was for years a strong backer of the CTBT, which was 40 years in the making. The pact was approved by the 189-nation U.N. General Assembly and opened for signature five years ago.

Under unusual approval procedures, the treaty cannot enter into force until it is signed and ratified by 44 states -- including the United States -- deemed nuclear arms-capable.

To date, 31 of those 44 countries including avowed nuclear powers France, Russia and Britain have signed and ratified the pact. So 13 more must ratify before it can take hold.

In that group, India, Pakistan and North Korea have neither signed nor ratified the treaty while the United States, China and eight others have signed but not ratified.

Former President Bill Clinton was the first world leader to sign the accord, in 1996. But the Senate refused to ratify it in the partisan-charged run-up to the 2000 election.

Jayantha Dhanapala, the top U.N. disarmament official, said nuclear rivals India and Pakistan have said they will sign the pact but still have not done so. No signings or ratifications are expected to be announced during the U.N. conference, he said.

The meeting is to end in adoption of a declaration expected to call on nations that have not yet signed or ratified to do so as soon as possible.

Copyright © 2001 Reuters Limited.

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