The system, the development of which is still pending a decision by US President Bill Clinton, failed to make the crucial distinction in its first two flight tests against mock targets, prompting the Pentagon to rig two other tests, the critics said in interviews with the daily.

The mock targets were substituted by simpler and fewer decoys that would be easier for the antimissile system to recognize, they said.

Massachusetts Institute of Technology (MIT) arms expert Theodore Postol obtained the Pentagon plan covering the four tests, which other experts including a senior government official agreed they were rigged.

"It is clear to me that none of the tests address the reasonable range of countermeasures," or decoys that an enemy warhead would use to confuse an antimissile weapon, said the official who asked the daily not to be identified.

Pentagon officials acknowledged that the plan obtained by the MIT expert was authentic, but defended the testing system.

Lieutenant Ronald Kadish of the Air Force, director of the Pentagon's Ballistic Missile Defense Organization denied that his program had engaged in any deception or dumbing down, the daily said.

Postol made his argument at a meeting of the US State Department's advisory board on arms control, the daily said.

Pentagon officials, he said in an interview with the daily, "are systematically lying about the performance of a weapon system that is supposed to defend the people of the United States from nuclear attack."

The anti-missile defense system is meant to protect from nuclear attacks by rogue nuclear powers such as Iraq and North Korea. It is criticized by Russia and has drawn Chinese warnings that its deployment could trigger an arms race in space.

The US plan to build a National Missile Defense (NMD) system that would intercept incoming ballistic missiles in space has led to fears that it would render obsolete the 1972 Anti-Ballistic Missile (ABM) treaty, one of the key planks in global disarmament negotiations.

"If the United States were to take a unilateral decision, the risks of an arms race would become serious," Dini said, speaking before the Italian senate's foreign affairs committee.

He said that other European allies of the United States, including Britain, France and Germany shared Italy's reservations about the project, and expressed the hope that Washington would not go-ahead without "intense consultations."

Russia had been fiercest opponent of the NMD plan, said by the United States to be a means of defending itself from missiles launched by "rogue states" such as Iraq and North Korea.

But Russian Defence Minister Igor Sergeyev is to visit Brussels on Friday to brief his NATO counterparts on a rival proposal, first unveiled by President Vladimir Putin on a visit to Rome Tuesday, to build a joint Russian-NATO missile defence system.

On Thursday, US Defence Secretary William Cohen warned that such a system could supplement but never supplant Washington's own plan.

Russia so far has adamantly refused to accept changes to the ABM treaty that would allow the United States to deploy a limited system anti-missile system.

Washington defends its proposal by saying would stop a few tens of missiles but be useless against Russia's vast arsenal, thus not endangering the balance of power between the two nuclear giants.