The US National Academy of Sciences issued a report yesterday strongly backing US ratification of the comprehensive test ban treaty (CTBT), in a rebuff to the Bush administration's policy of shelving the agreement.

The report was compiled over two years by a panel that included some of the country's leading nuclear scientists and the former commander of US forces in the Pacific, Charles Larson. It addressed the major security concerns raised by the Senate when it refused to ratify the treaty in 1999, and on each issue judged that the US would face "a more dangerous world" without the treaty.

The report was commissioned by the Clinton administration but President George Bush views the accord, which has yet to come into force, as unverifiable and a constraint on America's ability to develop and test new nuclear weapons.

Soon after Mr Bush took office, officials examined ways to withdraw the treaty from the Senate to ensure it was not ratified, but they were told by legal advisers that they had no constitutional power to do so.

Since then, the treaty has been in limbo, although radical conservatives in the administration have continued to press for the US to go further and renounce the treaty.

In December, the Pentagon put forward three options for consideration: one involved renunciation of the US signature on the treaty and cutting off all funds to the commission in Vienna established to monitor compliance; the second included renunciation but continued partial funding for the commission's global network of monitors; the third was to maintain the status quo, but the Pentagon made it clear this was not its preferred option.

Moderates at the National Security Council, wary of the diplomatic consequences of scrapping the treaty, blocked a high-level discussion on the Pentagon's options, in effect, shelving the debate. But as the unilateral US moratorium on nuclear tests approaches its 10th anniversary in September, some arms control advocates are concerned that the administration could use the occasion to withdraw from the CTBT.

Most diplomatic observers think that is unlikely. But they believe pressure from radicals to ditch the moratorium and the treaty will mount during the remaining two years of President Bush's first term.

Pentagon hawks are keen to test a new generation of tactical nuclear missiles aimed at destroying deep, heavily reinforced bunkers. The need for such weapons was expressed by the administration's nuclear posture review, which was leaked earlier this year. The 2003 defense budget earmarks $15.5m (£9.8m) to modify existing weapons for that purpose.

The report by the Academy of Sciences represents a blow to Pentagon radicals.

It rejects the chief technical criticisms of the treaty: that it would prevent the US conducting tests essential to maintain its nuclear readiness, and that it was unverifiable because other countries could conduct tests in secret.

On the first issue, the panel found that "the United States has the technical capabilities to maintain confidence in the safety and reliability of its existing nuclear-weapon stockpile under the CTBT". It argued that there was an array of increasingly sophisticated means of checking and maintaining weapons without nuclear tests.

It also suggested that if the international monitoring system of seismic and other sensors being developed by the treaty's preparatory commission in Vienna was fully deployed then an underground explosion with as small a yield as 0.1 kilotons (100 tons) could be "reliably detected".

The report conceded that if sophisticated masking techniques were used, a rogue state could hide a blast of up to two kilotons.

But the academy maintained that this would be extremely difficult. "A future no-CTBT world _ could be a more dangerous world than today's, for the United States and for others," the report said.

Daryl Kimball, the executive director of the Arms Control Association, welcomed the report as a "clear, definitive and authoritative rebuttal" of the administrations arguments.

But Baker Spring, a national security expert at the Heritage Foundation, argued that the report was incomplete. "It does not address military effectiveness," he said. "It assumes the military requirement will forever remain the same."

© Guardian Newspapers Limited 2002

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