Rep. Mark Meadows, R-N.C., sent a referral to the Justice Department about a message a top United Kingdom national security official delivered to the Trump transition team a week before President Trump's inauguration.

Congressional investigators told the Hill that in January 2017 then-U.K. national security adviser Sir Mark Lyall Grant hand-delivered a memo to soon-to-be national security adviser Michael Flynn's team that asserted the U.K. government had doubts about the credibility of British ex-spy Christopher Steele. Recent reports suggest Steele had briefed British intelligence officials on his dossier after the 2016 presidential election, and the heads of MI5 and MI6 were made aware of the contents of the dossier by late November.

“A whistleblower recently revealed the existence of a communique from our allies in Great Britain during the early days of the Russia collusion investigation,” Meadows said.

“Based on my conversations with that individual, and the credible timelines that are supported by other events, I made a referral to Attorney General William Barr and Inspector General Michael Horowitz for further investigation,” the North Carolina Republican added. “There now is overwhelming evidence to suggest that on multiple occasions the FBI was warned that Christopher Steele and the dossier had severe credibility issues.”

Steele compiled a dossier that contained salacious and unverified claims about Trump's ties to Russia. He was hired by opposition research firm Fusion GPS and was paid, in part, by the Democratic National Committee and Hillary Clinton's campaign. His dossier has become a flashpoint of concern for Republicans after the declassification of a House Intelligence Committee memo that said the FBI used the unverified research to obtain Foreign Intelligence Surveillance Act warrants beginning in October 2016 to wiretap onetime Trump campaign adviser Carter Page.

GOP investigators learned of the communique's existence within the past few weeks by a whistleblower who was part of Flynn's team and are pressing for answers ahead of Trump's visit to the United Kingdom early next month. Its existence came to light a month after the revelation of a State Department official's notes about an October 2016 meeting with Steele, sent to the FBI, that warned he was unreliable and that he had said he was being encouraged to get his allegations out prior to the 2016 presidential election.

The communique could be significant as it would have been delivered before the FBI applied for three FISA renewals against Page in 2017 using Steele's research. Sources said Flynn was not aware of its existence until he was questioned as part of special counsel Robert Mueller's investigation, after he pleaded guilty to lying to the FBI about his contacts with a Russian envoy, and therefore Trump too was likely not told about it.

The possible misuse of Steele's dossier has come into greater focus in recent weeks, including questions about whether the dossier contained possible Russian disinformation and whether former FBI Director James Comey or former CIA Director John Brennan tried to include the dossier in the January 2017 Intelligence Community Assessment on Russian interference in the 2016 election.

At least three federal investigations are looking into alleged FISA abuse, and other matters related to the way the FBI and the Justice Department conducted the Trump-Russia investigation, and several top ex-officials. Among them are Barr's examination of the origins of the counterintelligence inquiry into Trump's campaign. He has tasked U.S. Attorney John Durham to lead the review. Barr says he is working closely with Horowitz, who is nearing completion of his FISA abuse investigation.

Steele is reportedly open to speaking with Horowitz but has declined to cooperate with Barr.