A Foreign Office minister has dismissed as "facile" claims by a senior US official that Britain had no influence in Washington any more.
Kim Howells said he "simply don't believe" the comments made by Kendall Myers, a senior state department analyst, that Britain's role as a bridge between the US and Europe was "disappearing before our eyes".
Mr Myers told The Times that despite Tony Blair's claim that he could influence US policy, "we typically ignore them and take no notice - it's a sad business".
The prime minister has lost much public support for his decision to stand shoulder-to-shoulder with president George Bush following the September 11th attacks, particularly in his decision to follow the US into the war into Iraq.
But Mr Myers reportedly told an academic forum in Washington on Tuesday: "It was a done deal from the beginning, it was a one-sided relationship that was entered into with open eyes.there was nothing. There was no payback, no sense of reciprocity."
Liberal Democrat leader Menzies Campbell said: "These remarks reflect a real sense of distaste among thinking Americans for Mr Blair's apparent slavish support for President Bush.The special relationship needs to be rebalanced, rethought and renewed."
However, Mr Howells told BBC News 24 this morning: "What he's saying in effect is that every prime minister there's been since the second world war has suffered from this one-sided relationship. I simply don't believe that.
"I believe this guy probably wants to sell a book, become a big name on the American lecture circuit, whatever. He's another Washington official who wants to make a name for himself.
"Quite frankly these people are entitled to a career after they finish in the White House but they shouldn't try to risk a strategic relationship like this one with these kind of facile comments."
The increasingly dire situation in Iraq has put a major strain on UK-US relations, with many this side of the Atlantic warning that the government must develop a separate strategy from Washington.
Fears about Britain being a poor relation were compounded this summer when a private conversation between Mr Bush and Mr Blair was accidentally taped and made public.
Mr Bush greeted the prime minister with an informal "yo, Blair", before rebuffing his offer to go to the Middle East to help resolve the crisis between Israel and Hizbullah, in what was widely viewed as a humiliating put down.