A top FBI official working on special counsel Robert Mueller's investigation into Russian meddling in the election was removed over the summer after it was revealed that he'd allegedly sent anti-Trump text messages.

The news that counterintelligence agent Peter Strzok was removed from the probe was first reported by the New York Times on Saturday, and followed by separate reports in the Washington Post and Associated Press.

According to the Post, Strzok was reportedly having an affair with Lisa Page, an FBI lawyer who worked for Deputy Director Andrew McCabe, at the time he was also helping lead the investigation into Hillary Clinton's emails.

During the Clinton investigation and campaign season, Strzok and Page allegedly exchanged text messages which criticized then-candidate Donald Trump and indicated support of Clinton.

The Times reported "Strzok and a colleague reacted to news events, like presidential debates, in ways that could appear critical of Mr. Trump."

A spokesperson for Mueller's team confirmed to BuzzFeed News that Strzok was no longer assigned to the investigation.

"Immediately upon learning of the allegations, the Special Counsel’s Office removed Peter Strzok from the investigation,” special counsel's office spokesperson Peter Carr told BuzzFeed News. “Lisa Page completed her brief detail and had returned to the FBI weeks before our office was aware of the allegations.”

Strzok was reportedly reassigned to a job in the FBI's human resources department following the discovery of the alleged texts.

The FBI confirmed on Saturday that the two employees had been reassigned following the allegations, and that the Department of Justice's Office of the Inspector General was investigating the incident to "fairly determine the facts regarding potential wrongdoing."

"The FBI has clearly defined policies and procedures regarding appropriate employee conduct, including communications," the bureau said in a statement. "When the FBI first learned of the allegations, the employees involved were immediately reassigned, consistent with practices involving employee matters."

The exact nature of the text messages has not been made public, but defenders of Strzok and Page have reportedly called the allegations “overblown" and said there wasn't any misconduct.

The DOJ's Office of the Inspector General also said that it was “reviewing allegations involving communications between certain individuals" as part of a broader inquiry into how the FBI handled the 2016 election, and "will report its findings regarding those allegations promptly upon completion of the review of them.’’

Inside the FBI, the existence of the alleged text messages has reportedly raised fears that the news could fuel President Donald Trump's claims that Mueller's investigation is a political "witch hunt." Four people have been charged as part of the probe so far, including former National Security Adviser Michael Flynn who pled guilty on Friday to lying to the FBI.

Saturday's reports about Strzok's reassignment also prompted Republicans on the House Intelligence Committee to announce that they are drafting a a contempt of Congress resolution against Deputy Attorney General Rod Rosenstein and FBI Director Christopher Wray, over claims that they are stonewalling the committee's probe into Russian election meddling.

In a statement obtained by Bloomberg Saturday, House Intelligence Committee Chair Devin Nunes, a Trump ally, noted that the FBI and DOJ had refused the committee's demands “for an explanation of Peter Strzok’s dismissal from the Mueller probe.”

"By hiding from Congress, and from the American people, documented political bias by a key FBI head investigator for both the Russia collusion probe and the Clinton email investigation, the FBI and DOJ engaged in a willful attempt to thwart Congress’ constitutional oversight responsibility,” Nunes said.

Chris Geidner contributed to this report.