Britain's Prince Andrew has been named in American court proceedings by a woman who claims she was kept as an underage sex slave by a billionaire Wall Street financier.
Buckingham Palace has issued a statement denying the allegations, made in a motion filed by the woman's lawyers on Monday in the United States District Court in West Palm Beach, Florida, AFP reports.
A plaintiff, identified as "Jane Doe #3", alleges she was "forced to have sexual relations" with the Duke of York in London, New York and the Caribbean at the behest of Jeffrey Epstein when she was 17 and therefore a minor under Florida law.
Epstein, a known friend of the prince, was convicted in 2008 of soliciting an underage girl for prostitution and served a prison term.
This week's motion was not the first time Prince Andrew's name had been linked to the case but the allegations were serious enough for the British royal family to issue a formal denial.
"This relates to long-running and ongoing civil proceedings in the US to which the Duke of York is not a party," a spokesman said.
"However, for the avoidance of doubt, any suggestion of impropriety with underage minors is categorically untrue."
"Jane Doe #3" made the claim in a motion to be included in an ongoing civil case that accuses federal prosecutors of cutting a plea-bargain deal with Epstein without consulting his victims, in violation of the US Crime Victims Rights' Act.
Epstein was sentenced to 18 months in prison after pleading guilty to a single Florida state charge of soliciting prostitution. He remains a registered sex offender.
Others named in the filing include Alan Dershowitz, one of Epstein's defence lawyers, with whom "Jane Doe #3" was allegedly forced to have sex with on several occasions - a claim he denied.
The Harvard Law School professor, who is one of America's most prominent jurists, said on Friday he could easily prove the claim to be untrue.
Speaking to AFP, he accused "Jane Doe #3" of "filing a false and malicious legal proceeding" in an attempt to extort money from his former client.
Dershowitz challenged the woman to file criminal charges against him. He said he also planned to act swiftly to have her lawyers disbarred for unethical conduct.
"I know with one million percent certainty that the story about me is made up," he said. "I am squeaky clean and I will fight back because I have nothing to hide."
Prince Andrew, 54, is the second son of Queen Elizabeth II and fifth in line to the British throne. He was Britain's Special Representative for International Trade and Investment for 10 years until 2011.
Among Americans, he is best known as the former husband of Sarah Ferguson, 55. The couple, who have two children, divorced in 1996 but remain close friends.