Sean Spicer echoed a claim originally made by an analyst on Fox News that GCHQ spied on Trump Tower during the US election.
"He's able to get it and there's no American fingerprints on it," he said in a press conference.
A British security official on Tuesday denied the allegations originally made by Andrew Napolitano, telling Reuters it was "totally untrue and quite frankly absurd".
Trump sent out a flurry of tweets earlier this month accusing Obama of wire tapping his phones during the 2016 campaign.
How low has President Obama gone to tapp my phones during the very sacred election process. This is Nixon/Watergate. Bad (or sick) guy!— Donald J. Trump (@realDonaldTrump) March 4, 2017
The President gave no evidence of his claims, and he is coming under increasing pressure to back them up.