London (CNN) Britain's Prince Andrew does not have plans to take legal action against a woman who has named him in a sex abuse lawsuit in Florida, CNN learned Tuesday.

The allegation that he had sex with an underage girl, made in a federal court filing in Florida last week, has been firmly rejected by Buckingham Palace.

"It is emphatically denied that the Duke of York had any form of sexual contact or relationship with Virginia Roberts. Any claim to the contrary is false and without foundation," the palace said in a statement Monday.

A palace spokesman, who is not named per custom, pointed out Friday that Prince Andrew is not a direct party to the "ongoing civil proceedings in the United States."

At the same time, prominent U.S. attorney Alan Dershowitz, facing a similar accusation, has filed a motion asking a federal court to "strike the allegations made against him" regarding alleged sexual misconduct involving underage girls.

In the same document, filed Monday, Dershowitz requested "a show cause order" against the lawyers for the woman making this claim "and awarding such other relief that the Court deems just and proper."

Along with Prince Andrew and others, Dershowitz was named in the court filing in Florida as one of the prominent people who had sexual contact with teenage girls through self-made billionaire Jeffrey Epstein, who pleaded guilty some years ago in Florida to a state charge of prostitution solicitation.

Dershowitz, a Harvard University professor and high-profile lawyer, has never been charged with a crime in this case, nor has he been sued by the alleged victim.

He rejected the allegations in an interview with CNN's "New Day" on Monday and later, while speaking to CNN's Hala Gorani.

'Greatest man there is'

Amid the swirl of allegations, Andrew's ex-wife Sarah Ferguson reportedly gave strong backing Monday to her former husband, the Duke of York.

She spoke to reporters in Verbier in the Swiss Alps, where she had been on a ski holiday with Andrew and their daughter Eugenie, according to UK media reports.

"The York family is a tight unit. We've always been a tight unit," the Telegraph newspaper quoted Ferguson as saying.

"He is the greatest man there is. It was the finest moment of my life in 1986 when I married him. He is a great man, the best in the world."

Andrew is a son of Queen Elizabeth II and a brother of Prince Charles, the next in line for the British throne.

State plea deal

The federal court filing alleges that the woman, referred to as Jane Doe #3, was forced to have sex with several men when she was a teenager. Roberts made the allegations in the civil motion filed last week in U.S. District Court in southern Florida, joined by another unnamed woman.

While Roberts was not identified by name in the filing, her name was widely reported in the British news media over the weekend, and Buckingham Palace included it in the statement. (Dershowitz noted that in his CNN interview, it was CNN that identified her by name.)

Roberts and another woman are seeking to join two other women who are arguing in federal court for the U.S. government to take a fresh look at its case involving Epstein.

The investment banker agreed to a state plea deal in 2007 and began serving an 18-month sentence in 2008, according to The New York Times.

Epstein was the subject of a federal investigation, but a deal allowed him to plead guilty to a lesser state charge and avoid a potential federal case, the Times and The Washington Post reported.

Prince Andrew has been photographed with Epstein. The prince previously issued an apology for his friendship with the scandal-plagued billionaire.