The British Government was passed the dossier detailing alleged collusion between the Kremlin and Donald Trump back in December, it has emerged.
The collection of memos, which alleges the existence of a Russian programme "cultivating, supporting and assisting" Mr Trump to the presidency, was compiled by former MI6 officer Christopher Steele.
It was known to have circulated among intelligence officials and top politicians in Washington, and the Guardian now reports that Mr Steele's court filings state he shared the memo with a British "national security official" in their official capacity.
Unconfirmed reports in the document, which Mr Steele previously told The Independent had been passed to British authorities, cover "at least" five years of communication, co-operation and conspiracy between Mr Trump's camp and Russian intelligence officials.
Sources also claim that Moscow is capable of blackmailing the new president, and detail "perverted sexual acts" committed by the new President as evidence.
According to his court papers, Mr Steele decided to hand the dossier over "on a confidential basis in hard copy form" to the British intelligence services because it "had implications for the national security of the US and the UK", as well as being "of considerable importance in relation to alleged Russian interference in the US presidential election".
The dossier came into the public eye when it was published by Buzzfeed, who stressed they were "unverified and potentially unverifiable".
Mr Trump dismissed the wide-ranging allegations as "fake news", and a Russian businessman named in the dossier has brought a defamation lawsuit against Mr Steele and his private investigation company, Orbis Business Intelligence. The same venture capitalist is also suing Buzzfeed.
Mr Steele originally compiled the report for political opponents of Mr Trump in Washington, and was forced to go into hiding after being identified as its author.
He has only once spoken in public since the explosive dossier went public, giving a brief statement as he returned to work after going into hiding, and has refused to visit the US for fear of recriminations from the White House.
But the case against Orbis, which is being heard in London, has forced the former MI6 spy to reveal more details about the year he spent gathering evidence on the billionaire tycoon's alleged connections to Moscow.