Regan seeks $100m after being sacked by Murdoch's News Corp

If the firing of Judith Regan as head of her own book publishing imprint by the top brass at Rupert Murdoch's News Corporation nearly a year ago was nasty, the revenge she is seeking to exact today by way of a sweeping defamation lawsuit promises to be at least the equal of it.

It is not just the assertions in the suit that News Corp sought to smear her. More startling – and potentially more damaging – is her contention that company executives urged her to lie to federal officials about a former New York police chief, Bernard Kerik, with whom she had had an affair.

ReganBooks, a unit within HarperCollins, was disbanded at the end of last year when Ms Regan was fired following the controversy sparked by her attempts to release a book by O J Simpson. In If I Did It, Mr Simpson speculates about how he would have killed his wife Nicole Brown Simpson and her friend Ronald Goldman, were he in fact guilty. It was a spectacular fall to earth for Ms Regan, who for more than a decade had delivered one money-making title after another for Mr Murdoch, including memoirs by the porn star Jenna Jameson.

The 70-page lawsuit seeks damages totalling $100m (£47m) and accuses News Corp and some of its executives of trying to make her a scapegoat for the Simpson debacle. Specifically, she charges them with falsely suggesting that she had made anti-Semitic remarks in an argument with a company lawyer.

The suit also contends that executives were bent on undermining her reputation for fear of the damage she might inflict on Mr Kerik, and by extension his former mentor, Rudy Giuliani, once New York's mayor and now running to be the Republican Party's nominee for president. "Because of the damaging information that defendants believed Regan possessed, defendants knew they would be protecting Giuliani if they could pre-emptively discredit her," the lawsuit says.

While the passages about Mr Kerik make up only a small part of the suit, they will get all the media attention. They imply a bias within News Corp, the owner of Fox News, in favour of Mr Giuliani. They also threaten to embarrass Mr Giuliani as he strives to distance himself from Mr Kerik, who last week was hit with charges of tax fraud, conspiracy and lying to the White House. President George Bush nominated Mr Kerik as head of Homeland Security in 2004 on the urging of Mr Giuliani. Mr Kerik withdrew within days, however, when ethical problems surfaced. Among stories that appeared was one that the married Mr Kerik had trysts with his lover, Ms Regan, in a flat near Ground Zero that was meant as a retreat for exhausted rescue workers.

According to Ms Regan, executives at News Corp became nervous about what she might tell federal investigators about her former boyfriend if they asked. One executive, the suit says, told her to lie if necessary. Another told her "not to produce clearly relevant documents in connection with the government's investigation of Kerik".

"Defendants were well aware that Regan had a personal relationship with Kerik," the lawsuit says. "In fact, a senior executive in the News Corporation organisation told Regan that he believed she had information about Kerik that, if disclosed, would harm Giuliani's presidential campaign. This executive advised Regan to lie to, and to withhold information from, investigators concerning Kerik."

A spokesman for News Corp said the claims against the company were "preposterous".