NEW YORK (CNN) -- Senior executives at News Corp. urged publisher Judith Regan to lie to investigators about ex-New York Police Commissioner Bernard Kerik in order to protect Rudy Giuliani's presidential ambitions, Regan alleges in a lawsuit filed this week.
Judith Regan says News Corp. executives told her to lie about her affair with Bernard Kerik.
The lawsuit does not name the executives or cite any documents to back up her allegation. News Corp., which is led by Rupert Murdoch and is the parent company of the Fox television network and cable news channel, called the suit's claims "preposterous" Wednesday.
But Regan says she was the victim of a smear campaign "to save the reputation of Kerik and, by association, Rudy Giuliani."
Regan says she had an affair with Kerik that began in 2001.
The 70-page lawsuit was filed in a state court in New York just days after Kerik's indictment on federal corruption charges in a case that has fueled criticism of Giuliani, his longtime patron.
Regan ran the News Corp.-owned imprint ReganBooks before her 2006 firing. She also appeared on a talk show on Fox News for several years.
Her $100 million suit accuses News Corp. and publishing subsidiary HarperCollins of breach of contract and defamation, and says the company made her the "scapegoat" for a controversy over her planned publication of ex-football star and onetime murder defendant O.J. Simpson's memoir, "If I Did It."
Her lawsuit states that Giuliani's political ambitions are central to the company's political agenda, and accuses News Corp. of using its media outlets to spread "completely fabricated" stories that said she made anti-Semitic remarks and portrayed her as "crazy, slutty, hysterical, scorned, vindictive, etc."
She alleges that in December 2004, after President Bush tapped Kerik for the homeland security post, a senior News Corp. executive told her he believed she knew things about Kerik "that if disclosed, would harm Kerik's Homeland Security nomination, and more importantly, Giuliani's planned presidential campaign."
Another executive "advised Regan not to produce clearly relevant documents in connection with a governmental investigation of Kerik," her lawsuit states.
"It is now widely accepted that one of Giuliani's major political vulnerabilities is his association with Bernard Kerik," the complaint reads. It states that News Corp. bosses were "well aware" of her relationship with Kerik and "knew they would be protecting Giuliani if they could pre-emptively discredit her."
The complaint does not state whether Regan shared any information about Kerik with authorities, and her attorneys declined to elaborate on the allegations in the lawsuit.
Meanwhile, News Corp. spokeswoman Teri Everett said, "We believe her claims are preposterous."
Giuliani, who tops national polls in the race for the 2008 Republican presidential nomination, installed Kerik as New York's corrections commissioner and police chief during his two terms as mayor and was a leading advocate of Kerik's ill-fated 2004 nomination for the post of Homeland Security secretary. He called that support for Kerik "a mistake" last week.
Campaigning in Council Bluffs, Iowa, on Wednesday, Giuliani refused comment on Regan's lawsuit.
"I don't know anything about it, and it sounds to me like kind of a gossip column story more than a real story," he said.
A federal grand jury in White Plains, New York, returned a 16-count indictment against Kerik last week, accusing him of failing to report more than half a million dollars in income from 1999 to 2004 and making false statements to the White House and other federal officials.
Kerik withdrew his nomination for the Cabinet post after disclosing that he had hired a nanny whose immigration status was questionable. In 2006, he pleaded guilty to misdemeanor charges that he traded payment on repairs to his Bronx apartment for favors, including city contracts. E-mail to a friend
CNN's Janine Brady and Chris Welch contributed to this report.