British Prime Minister Tony Blair tonight suffered a major rebuff after the Americans poured cold water over an offer to site key elements of their controversial "son of Star Wars" missile defence system on British soil.
Earlier, No 10 confirmed for the first time that the Government was in discussion with Washington about hosting parts of the programme - believed to be the interceptors used to bring down a ballistic missile - in the UK.
Within hours, however, the US deputy chief of mission in London, David Johnson, went on the airwaves to say the US administration was primarily focusing on allies in Eastern Europe to locate the system.
"As we go forward there may be opportunities for us to talk to other countries about their needs, but right now we are concentrating on the Czech Republic and on Poland as the primary sites where we would be looking for this," he told BBC Radio 4's The World at One.
The rejection of the UK to host the programme is likely to be seen as a massive embarrassment for Mr Blair, after No 10 had made clear that Britain had come forward with the offer.
"It is our intention that whilst the United States are in the decision-making process, the UK should be considered as part of that," a spokeswoman said. "The Prime Minister thinks it is a good idea that we are part of the consideration by the United States.
"We believe that it is an important step towards providing missile defence coverage for Europe of which we are part." It followed a report in The Economist that Britain had been lobbying since the autumn to host the system.
No 10 would not expand on why Mr Blair wanted it to be located in Britain. However, the offer appears to have been an attempt to further bind the UK to the US before he leaves office.
The spokeswoman would not say whether the Prime Minister had approached President George Bush directly, but said that discussions, which were still at an early stage, had taken place at "various levels".
According to one report, the talks were being led by Mr Blair's chief foreign policy adviser Sir Nigel Sheinwald, while his likely successor, Chancellor Gordon Brown, was reported to have been involved in the internal Whitehall discussions.
In offering to site the system in the UK, Mr Blair risked stirring up further resentment on the Labour benches, where many MPs remain deeply opposed to his strong alliance with President Bush.
The Government faced a political storm in 2003 when it agreed that the Americans could update the early warning radar at RAF Fylingdales as part of the missile defence programme.
PA