WASHINGTON, March 17 -- The White House has apologized to the British government after alleging that former U.S. President Barack Obama used a British intelligence agency to spy on President Donald Trump while he was a candidate last year, U.S. media reported Friday.

CNN reported that U.S. national security adviser H.R. McMaster spoke with his British counterpart Mark Lyall Grant on Thursday about White House press secretary Sean Spicer's comment about a Fox News report that said British intelligence helped wiretap Trump Tower during the 2016 campaign.

CNN quoted a White House official as saying that the conversation was "cordial" and McMaster described Spicer's comment as "unintentional."

McMaster also told his counterpart that "their concerns were understood and heard and it would be relayed to the White House."

On Thursday evening, Spicer repeated the Fox News claim that British intelligence agency GCHQ was used by Obama to spy on Trump Tower in the lead-up to last November's election.

The comments prompted GCHQ to issue a public statement that said,"Recent allegations made by media commentator Judge Andrew Napolitano about GCHQ being asked to conduct 'wiretapping' against the then president-elect are nonsense. They are utterly ridiculous and should be ignored."

A spokesman for British Prime Minister Theresa May said Friday the White House has assured the British government that the allegations that British intelligence services spied on Trump will not be repeated, according to British newspaper The Telegraph.

Britain "made it clear" to the United States that the "ridiculous" claims should be ignored and received assurances in return that they will not be repeated, showing that the administration does not give them any credence, May's spokesman said.