Senior officers in the US Air Force Space Command are said to be fuming that the Missile Defence Agency is refusing to release millions of dollars for the work which is one of President Bush's priorities.

Now the Air Force officers have complained to the US Government's Accountability Office. "Without the test equipment the operation of upgraded early warning radars could be degraded," the office warned a House of Representatives sub-committee.

The early warning radars at Fylingdales and at Beale in California need to be upgraded to carry out their planned role as part of the missile defence shield to protect the United States from attack by rogue states.

No funds have been allocated to carry out the work and an entire systems programming agency is needed to support the necessary upgrades in software and hardware at the two sites.

The GAO report said: "The Air Force currently has a systems programming agency in place to support hardware and software development for the early-warning radar.

"However, neither the Missile Defence Agency nor the Air Force has included funds in their budgets to establish a systems programming agency for the upgraded Beale and Fylingdales radars."

The current system is dependent on commercial off-the-shelf equipment and officials said that if a replacement part operated nanoseconds faster or slower than the original, the radar could fail or possibly generate false reports of incoming missiles.

The US Air Force has included $59m in its budgets for 2006 to 2011 for devices to detect attacks on Vandenburg Air Force Base - home of the 30th Space Wing - in California and to upgrade the radars at Fylingdales and Beale.

But an official in the Air Force's Missile Warning and Defence Office said the cost was expected to exceed planned funding.

Peace campaigner Lindis Percy from Hull, is critical of attempts to upgrade RAF Fylingdales and the US signals intelligence station at Menwith Hill, near Harrogate, as part of the missile defence system.

The co-founder of the Campaign for the Accountability of American Bases (CAAB) said: "The US is the richest country on earth and yet recently asked the world for aid to help rebuild New Orleans.

"Could it just be that at last someone has put the brakes on this crazy and dangerous system?"

CAAB's next demonstration at Menwith Hill is planned for Saturday at noon.