Investigators for Russia special counsel Robert Mueller this summer interviewed the former British spy who wrote a dossier of unsubstantiated allegations about President Donald Trump during last year's election, CNN reported Thursday.
The report, which provided no further details of the meeting with Christopher Steele, was based on "two people familiar with the matter."
Steele, a former MI-6 officer, identified Russian business executives and others in the dossier whom U.S. intelligence analysts have concluded were intelligence officers or working on behalf of the Russian government.
Reuters reported Wednesday that Mueller's investigators had taken over FBI inquiries into the dossier, which was ordered by the Washington opposition research firm Fusion GPS.
CNN also reported FBI and other intelligence officials took Steele's dossier last year more seriously than they had publicly acknowledged.
In January, James Clapper, who was director of national intelligence, said U.S. spy agencies had "not made any judgment that the information in this document is reliable."
The intelligence agencies, particularly the CIA and the FBI, took Steele's document seriously enough to keep it from public report released that month on Russian meddling.
With that step, the agencies sought to "not divulge which parts of the dossier they had corroborated and how," CNN reported.
In addition, Talking Points Memo reported Thursday "a lawyer familiar with the outlines of Mueller's probe" said the dossier was "the road map that Mueller was using in his investigation."
Former FBI Director James Comey presented the dossier's information in January to Trump, who was president-elect, and former President Barack Obama.
Trump fired Comey in May, leading to Mueller's appointment as special counsel.
A representative for Steele did not respond to a request for comment, CNN reported. Mueller's office declined to comment.
Russia has repeatedly denied any meddling in the election — and Trump has slammed the Moscow investigation as a "witch hunt."
Steele has not met with congressional investigators in their Russia probes, with Senate Intelligence Committee Chairman Richard Burr of North Carolina expressing frustration Steele has rejected requests to meet with his panel.
"The committee cannot really decide the credibility of the dossier without understanding things like, who paid for it?" the third-term Republican said Wednesday. "Who are your sources and sub-sources?
"We're investigating a very expansive Russian network of interference in US elections," Burr added.
"And though we have been incredibly enlightened at our ability to rebuild backwards, the Steele dossier, up to a certain date, getting past that point has been somewhat impossible."