A Fox Business Network presenter has been suspended amid reports of a sexual harassment allegation - the latest such claim to hit the cable giant.
An analyst says the channel sidelined her after she ended an extramarital affair with Making Money host Charles Payne, the Los Angeles Times reports.
Mr Payne said on Twitter the story is "an ugly lie I vehemently deny to my core".
Fox has been embroiled in a sexual harassment scandal for a year.
The cable news network said in a statement: "We take issues of this nature extremely seriously and have a zero tolerance policy for any professional misconduct.
"This matter is being thoroughly investigated and we are taking all of the appropriate steps to reach a resolution in a timely manner."
Mr Payne - who has worked at Fox Business Network since its 2007 launch - acknowledged to the National Enquirer on Wednesday that he had had a "romantic relationship" with a married female political analyst, who frequently appeared on Fox Business Network and Fox News Channel.
The presenter's statement to the supermarket tabloid included an apology to his wife, children and friends.
The unnamed accuser contacted 21st Century Fox's lawyers to allege her appearances on Fox were cut after she ended her affair with Mr Payne, reports the Los Angeles Times.
She said she only stayed in a relationship with Mr Payne because she hoped it would help her secure a permanent position at Fox, sources told the newspaper.
Neal Korval, Mr Payne's lawyer, told the Times his client denied sexually harassing the woman.
The attorney did not immediately return a request from the BBC for comment.
But Mr Payne said on Twitter: "That is an ugly lie I vehemently deny to my core. There is a mountain of proof that also proves its [sic] a lie."
He added: "I will fight this like a lion armed with truth. Thanks so much to all those that have reached out in support."
Earlier this week Fox Sports senior executive Jamie Horowitz was fired amid sexual harassment claims.
The clampdown by the channel's owner, Rupert Murdoch's 21st Century Fox, comes as it seeks British regulatory approval to take over broadcaster Sky.