American intelligence officials last week presented to Trump, as well as to President Barack Obama, a two-page synopsis about the potentially embarrassing allegations involving Russia, according to CNN, The New York Times and other media.
Clapper in a statement said that he and Trump spoke yesterday about unverified claims that his aides colluded with the Kremlin to win the US election, and that Russia has compromising information on Trump.
"This evening, I had the opportunity to speak with President-elect Donald Trump to discuss recent media reports about our briefing last Friday," Clapper said.
Trump at a press conference yesterday denied explosive allegations about his ties to Russia, and attacked US intelligence agencies and the media over the allegations.
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But Clapper said he told the incoming US president that it is doubtful that the leak came from within the intelligence community.
"I emphasised that this document is not a US intelligence community product and that I do not believe the leaks came from within the IC," Clapper said.