Senator John McCain passed documents to the FBI director, James Comey, last month alleging secret contacts between the Trump campaign and Moscow and that Russian intelligence had personally compromising material on the president-elect himself.

The material, which has been seen by the Guardian, is a series of reports on Trump’s relationship with Moscow. They were drawn up by a former western counter-intelligence official, now working as a private consultant.

The Guardian has not been able to confirm the veracity of the documents’ contents, and the Trump team has consistently denied any hidden contacts with the Russian government.
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Most explosively, the report alleges: “FSB has compromised Trump through his activities in Moscow sufficiently to be able to blackmail him.” - The Guardian