GCHQ rejected allegations made by White House press secretary Sean Spicer, that it spied on Mr Trump, as "nonsense".
During a White House press briefing on Thursday, Spicer cited comments from Fox News commentator Andrew Napolitano that Spicer said confirmed Britain's Government Communications Headquarters (GCHQ), an intelligence agency, took part in a spy operation at Trump Tower during the 2016 United States election.
Fox played video of Trump joking at the press conference.
His comments came shortly after the Republican and Democratic leaders of the Senate intelligence commmittee said there was no evidence that any surveillance had taken place. Trump accused Obama of felonious surveillance - presidents can not legally order their political opponents spied upon - to discredit evidence that Russian Federation sought to aid his election. "The statement clearly says at this time they don't believe it", said Mr Spicer.
A government source, who requested anonymity when discussing sensitive information, said an initial examination indicated it contained no evidence to support Trump's charge.
Spicer pointed to Andrew Napolitano, a New Jersey judge turned commentator as the source who said on the show "Fox& Friends" on March 14, "Three [unnamed] intelligence sources have informed Fox News that President Obama went outside the chain of command".
This is before we even get to the part of the interview when Trump braggingly talked about the man he saw on Fox News call him "the greatest president ever". Rep. Tom Cole, R-Okla., said Friday that Trump had not proven his case and should apologize to Obama. He was asked by German reporter Ansgar Graw of Die Welt about the angry denial by British officials that Britain, at the behest of the Obama administration, had spied on Trump during the presidential campaign. USA intelligence agencies, including the Federal Bureau of Investigation, have found Russia's meddling was meant to hurt Democrat Hillary Clinton and ultimately to help Trump win.
But speaking at the White House news conference, with German Chancellor Angela Merkel, at his side, Trump distanced himself.
The Republican Trump, president since January 20, tweeted this month that his Democratic predecessor had wiretapped him during the late stages of the 2016 campaign. "And so you shouldn't be talking to me, you should be talking to Fox, okay?" He also insisted the White House did not leak his tax documents.
Spicer's comments drew a swift and rare public rebuke from British intelligence, which called the claim "utterly ridiculous".
James Clapper, who was President Obama's director of national intelligence, said no activity matching Trump's claims had happened. If he's doubling down in the face of outright denial from the British intelligence community about a claim he saw on Fox News, whose testimony here would satisfy him?