Justice Department officials are reading through “over 10,000 texts” between FBI officials Peter Strzok and Lisa Page, Fox News has learned, after it emerged Strzok was removed from Special Counsel Robert Mueller's Russia probe following the discovery of anti-Trump messages between them.

Department of Justice officials told Fox News they are in the process of going through the texts so they can hand them over to the House Intelligence Committee.

Strzok, who was an FBI counterintelligence agent, had worked on the Mueller probe, but was reassigned to the FBI’s human resources division after the discovery of anti-Trump text messages with Page, with whom he was having an affair. Page was briefly on Mueller’s team, but since has returned to the FBI.

The disclosure of those messages revived Republican concerns about the objectivity of Mueller’s probe.

It’s unclear whether a significant number of the 10,000 texts have anything to do with Trump or the probe itself.

Justice Department officials say the process of reading and redacting the texts could take “weeks,” and that the thousands of text messages between Strzok and Page span over “several months.”

The review process comes as the committee also threatens to move forward with a contempt resolution against top DOJ and FBI officials barring an imminent breakthrough — after the agencies did not comply with a deadline to hand over long-sought information that goes well beyond text messages.

Strzok is a focus of their efforts. House investigators have long regarded him as a key figure in the chain of events when the bureau, in 2016, received the infamous anti-Trump "dossier" and launched a counterintelligence investigation into Russian meddling in the election that ultimately came to encompass FISA surveillance of a Trump campaign associate.

House Intelligence Committee Chairman Devin Nunes, R-Calif., has sought documents and witnesses from the DOJ and FBI to determine what role, if any, the dossier played in the move to direct the surveillance.

Strzok briefed the committee on Dec. 5, 2016, sources said. But within months of that session House Intelligence Committee investigators were contacted by an informant suggesting that there was “documentary evidence” that Strzok was purportedly obstructing the House probe into the dossier.

Early Saturday afternoon, after Strzok’s texts were cited in published reports by the New York Times and the Washington Post – and Fox News had followed up with inquiries about the department’s refusal to make Strzok available to House investigators – the Justice Department contacted the office of House Speaker Paul Ryan to establish a date for Strzok’s appearance before House Intelligence Committee staff, along with two other witnesses long sought by the Nunes team.

The Justice Department maintains that it has been very responsive to the House panel's demands, including private briefings for panel staff by senior DOJ and FBI personnel and the production of several hundred pages of classified materials available in a secure reading room at DOJ headquarters on Oct. 31.

But Nunes voiced skepticism on Saturday.

He said that after the Strzok texts were revealed, the DOJ expressed a “sudden willingness to comply with some of the Committee’s long-standing demands” but added: “This attempted 11th-hour accommodation is neither credible nor believable, and in fact is yet another example of the DOJ’s disingenuousness and obstruction.”

A DOJ spokeswoman said Sunday they will “continue to work with congressional committees to provide the information they request consistent with our national security responsibilities.”

Fox News has learned that Strzok also oversaw the bureau’s interviews with ousted National Security Advisor Michael Flynn – who pleaded guilty Friday to lying to FBI investigators in the Russia probe.

He also was present during the FBI’s July 2016 interview with Hillary Clinton at the close of the email investigation, shortly before then-FBI director James Comey called her actions “extremely careless” without recommending criminal charges.

Fox News’ James Rosen contributed to this report.