"But a former US diplomat, Ambassador Joseph Wilson, went on the record at the weekend to say that he had travelled to Africa to investigate the uranium claims and found no evidence to support them.

Now the CIA official has told the BBC that Mr Wilson's findings had been passed onto the White House as early as March 2002.

That means that the administration would have known nearly a year before the State of the Union address that the information was likely false.

In response, a US Government official told the BBC that the White House received hundreds of intelligence reports every day. "