Former FBI Director James Comey withheld at least one detail from the public when he testified before Congress on Thursday.

AP Photo/J. Scott Applewhite - apimages.com

But at a closed-door meeting that took place immediately after the hearing, Comey brought members of the Senate Intelligence Committee in the loop: then-Senator Jeff Sessions reportedly failed to disclose that he met Russia's ambassador to the U.S. a third time during the 2016 presidential campaign, according to intercepted Russian communications.

On March 2, Sessions recused himself from any investigation into Russian interference in the election after he was caught lying in his confirmation hearing in January about whether he met any Russian officials; it was revealed later that he in fact had two meetings with Russian ambassador Sergey Kislyak.

"Any confirmation of a private meeting with Kislyak in April would raise a host of questions, most particularly for Sessions," NBC News reported. "April 2016 is when officials at the Democratic National Committee first noticed suspicious activity on their network—activity they would later learn was part of a Russian hack."

AP/Ron Sachs - apimages.com

STILL, sources told NBC News that "the evidence [of this private meeting] does not amount to proof." CNN reported "it is possible" that Kislyak "was exaggerating the extent of the encounter."

The Justice Department flatly denied that an April 2016 meeting occurred in a statement responding to rumors that first surfaced last week.

"The Department of Justice appointed special counsel to assume responsibility for this matter. We will allow him to do his job. It is unfortunate that anonymous sources whose credibility will never face public scrutiny are continuously trying to hinder that process by peddling false stories to the mainstream media. The facts haven't changed; the then-Senator did not have any private or side conversations with any Russian officials at the Mayflower Hotel."