In a statement, Ms. Estrich, Mr. Ailes’s lawyer, said: “Roger Ailes has never sexually harassed Megyn Kelly. In fact, he has spent much of the last decade promoting and helping her to achieve the stardom she earned, for which she has repeatedly and publicly thanked him.”

Ms. Kelly’s lawyer, Willis J. Goldsmith, said in a statement, “Megyn Kelly has made no public comment on the matter, nor will she while the review is pending, other than to say she has cooperated with the inquiry fully and truthfully.”

Her revelations to investigators contrast with comments she made earlier about the Fox News chairman. In an interview two months ago, before a prime-time special that Mr. Ailes orchestrated, she said she “loved working for Roger Ailes.”

“The number of times he’s had my back, given me opportunities, stuck his own neck out there to protect me, I feel very grateful to him,” she said. “And I feel loyal to him.”

The events leading to Tuesday’s developments began when Ms. Carlson, who had been an anchor in Fox News’s afternoon lineup, filed a lawsuit saying she had been fired from her weekday show on Fox News after rebuffing sexual advances from Mr. Ailes.

On the day Ms. Carlson filed her suit, 21st Century Fox said it would conduct an internal review, and the company retained the law firm Paul, Weiss, Rifkind, Wharton & Garrison to lead the investigation.

Though more than a dozen on-air personalities have come forward in the last two weeks to publicly support Mr. Ailes — with several questioning Ms. Carlson’s motivations — Ms. Kelly was, noticeably, not among them. She has the stature within the network to withstand any pressure to support Mr. Ailes. In part, that is because of her high ratings (she has the second-highest-rated show in cable news, behind only Mr. O’Reilly’s), but she is also well liked by the Murdoch family, which has indicated it would like her to be an important part of Fox’s future. Ms. Kelly’s contract expires next year.