One of Britain's leading spy agencies has angrily denied claims - suggested by the White House press secretary - that it helped former president Barack Obama spy on Donald Trump.
In a very rare public statement, a spokesman for Cheltenham based GCHQ told ITV News that any suggestion it was involved in spying on Mr Trump "was utterly ridiculous and should be ignored”.
The strongly-worded denial came shortly after Sean Spicer repeated an unsubstantiated and explosive allegation - first made by a Fox News analyst - that Barack Obama used British spies to watch Donald Trump on his behalf to ensure "there were no American fingerprints on it".
Mr Trump has come under substantial pressure, including from those within his own party, to either provide credible evidence or retract his incendiary accusation.
He has done neither nor signalled any desire to do so.
And the White House has now risked escalating the controversy even further by embracing a theory that Britain - one of America's closest allies - conspired with a president against a presidential candidate.
Asked whether President Trump had raised the allegation of British involvement with Prime Minister Theresa May and whether it could impact the so-called "Special Relationship", Mr Spicer said: "It has not been raised."
GCHQ's decision to break with convention to publicly comment on a story indicates a clear annoyance within the agency at the White House's desire to the claim.
“Recent allegations made by media commentator Judge Andrew Napolitano about GCHQ being asked to conduct 'wire tapping' against the then President Elect are nonsense. They are utterly ridiculous and should be ignored," the spokesperson said.