A US Government committee will look into a news report claiming the FBI investigated whether President Donald Trump has been working on behalf of Russia, against US interests.
It comes after the New York Times reported that the probe began in the days after Mr Trump fired James Comey as FBI director in May 2017.
It said the agency’s counterintelligence investigators had to consider whether Mr Trump’s actions constituted a possible threat to national security.
The president’s response
The White House rejected the Times article as “absurd” and Mr Trump lashed out at the New York Times, Mr Comey and the FBI in stream of tweets.
He added: “I have been FAR tougher on Russia than Obama, Bush or Clinton. Maybe tougher than any other President.”
“At the same time, & as I have often said, getting along with Russia is a good thing, not a bad thing. I fully expect that someday we will have good relations with Russia again!”
Mr Comey took to Twitter later on Saturday, offering a quote he attributed to former President Franklin Delano Roosevelt: “I ask you to judge me by the enemies I have made”.
Mr Trump’s lawyer, Rudy Giuliani, told the New York Times he had no knowledge of the inquiry.
What will the committee look at?
House Judiciary Committee Chairman Jerrold Nadler said his panel “will take steps to better understand both the President’s actions and the FBI’s response to that behaviour” in coming weeks.
He also said politicians would seek to protect investigators from the President’s “increasingly unhinged attacks”.
“There is no reason to doubt the seriousness or professionalism of the FBI, as the President did in reaction to this story,” Mr Nadler, a New York Democrat, said.
“We have learned from this reporting that, even in the earliest days of the Trump administration, the President’s behaviour was so erratic and so concerning that the FBI felt compelled to do the unprecedented [and] open a counterintelligence investigation into a sitting president.”
House Intelligence Committee Chairman Adam Schiff said he could not comment on the specifics of the report, but said his committee would press ahead with its probe of Mr Trump’s contacts with Russia.
“Counterintelligence concerns about those associated with the Trump campaign, including the President himself, have been at the heart of our investigation since the beginning,” Mr Schiff said.
He said meetings, contacts, and communications between Trump associates and Russians, as well as “the web of lies about those interactions, and the President’ s own statements and actions” have heightened the need for an investigation.
The New York Times said FBI officials became suspicious of Mr Trump’s ties to Russia during the 2016 presidential campaign.
But it held off on opening an investigation until Mr Trump tied his dismissal of Mr Comey to a probe into allegations of election meddling by Russia.
The FBI also considered whether the president’s firing of Mr Comey amounted to obstruction of justice.
US Special Counsel Robert Mueller took over the investigation into Mr Trump days after the FBI opened it. Russia denies it sought to influence the election.