The Government is expected to announce today that it has agreed in principle to allow the US to use the Fylingdales early warning radar base in North Yorkshire for its missile defence programme.

Defence Secretary Geoff Hoon will make a statement to the House of Commons.

Official sources at the Ministry of Defence said it would not be a full go-ahead to the programme, but Mr Hoon will announce he is "minded" to accept the US request to use the base as an integral part of President George W Bush's "Son of Star Wars" missile shield.

Later this afternoon, the minister will appear before the Commons Defence Committee to explain his decision.

A Downing Street spokesman said a final decision would not be made until after a debate in Parliament.

But this is likely to be a formality and is bound to fuel the protests of campaigners who believe it will make the base a greater target for attacking missiles and terrorists.

Last week, Mr Hoon dismissed concerns that North Yorkshire would be at increased risk - saying such an attack would be highly improbable, with countries of concern "unlikely to have the capability to target specific places or installations".

Last month, Mr Hoon said Britain would "consider the US request very seriously", and agree to it "only if we are satisfied that it will ultimately enhance the security of the UK and the Nato alliance".

Peace protestors have attacked the process as a farce, saying that the decision to agree to use Fylingdales as part of US National Missile Defence had already been made.