Hundreds of demonstrators are to protest on Saturday against plans to use an RAF base in North Yorkshire as part of a new American missile defence system.

The government is considering a formal request from the head of the US Missile Defence Agency to use RAF Fylingdales as part of the controversial "Son of Star Wars" programme.

The Bush administration says the system will increase protection.

But protesters claim it will make Britain more of a target without giving it a protective screen of missiles.

People will see the Son of Star Wars as an offensive weapon and Britain will be in the firing line of any kind of retaliation Keith Mollison Fylingdales Action Network

They intend to demonstrate outside the base and ask officials if they can send their own "weapon inspectors" inside, to draw parallels with Iraq's alleged armoury.

Keith Mollison, from the Fylingdales Action Network, said the aim of the rally was to draw attention to this "part of a weapon of mass destruction".

He said it was the first steps towards the US putting weapons in space and controlling space.

"The dangers are manifold. For us locally, it will make Fylingdales more of a target and part of an offensive weapon," he said.

"It will also make Britain more of a target. People will see the Son of Star Wars as an offensive weapon and Britain will be in the firing line of any kind of retaliation."

Fylingdales has an advanced radar which could track missiles .

They would then in theory be shot down as they neared the US coast.

Opponents say the "Son of Star Wars" scheme is unnecessary, would not work and would simply make the UK a target.

RAF Fylingdales is a landmark structure on the North Yorkshire Moors, a giant three-sided building giving an eye-catching contrast to the landscape.

It was first opened in 1962 as a Ballistic Missile Early Warning System.