In an attempt to provide credibility to the claims, Mr Spicer quoted from a series of articles which discussed surveillance.

Most of the articles detailed how US intelligence agencies were looking into unusual communications between a computer server in Trump Tower and a Russian bank.

But one of the articles used to build Mr Spicer’s case was a transcript from Fox News on Tuesday morning, in which a political commentator and former New Jersey judge, Andrew Napolitano, alleged British involvement.

He claimed that rather than ordering US agencies to spy on Mr Trump, Mr Obama obtained transcripts of Mr Trump's conversations from Britain's GCHQ, which monitors overseas electronic communications.

Mr Spicer read out the report, quoting Mr Napolitano.

"Last on Fox News, on March 14th, Judge Andrew Napolitano made the following statement, quote, 'Three intelligence sources have informed Fox News that President Obama went outside the chain of command. He didn't use the NSA, he didn't use the CIA, he didn't use the FBI and he didn't use the Department of Justice. He used GCHQ. What is that? It's the initials for the British intelligence finding agency. So, simply by having two people saying to them president needs transcripts of conversations involving candidate Trump's conversations, involving president-elect Trump, he's able to get it and there's no American fingerprints on this. Putting the published accounts and common-sense together, this leads to a lot.'"