Sarah Ferguson praises Prince Andrew as 'the best man in the world' amid sex allegations

The Duchess comments for the first time as the Duke of York denies allegations of having sex with an underage girl

Prince Andrew and Sarah Ferguson with Princess Beatrice and Eugenie at a party for Sir David Frost in 1999

Sarah Ferguson has praised her ex-husband Prince Andrew as the “best in the world”, as he vehemently denies allegations of having sex with an underage girl.

The Duchess made her first comments four days after the Duke of York was reportedly named in US court documents as having sex with a woman identified as Virginia Roberts on three separate occasions while she was still a minor under US law.

Ms Roberts is said to have been "procured" for him by American billionaire and convicted sex offender Jeffrey Epstein, who she accuses of using her as a "sex slave".

Prince Andrew categorically denies the allegations of any involvement.

"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."

She reportedly made the comments as she left the luxury ski chalet in Verbier in Switzerland, where she had been holidaying with Andrew, 54, and their younger daughter Eugenie.

Buckingham Palace has taken the unusual step of issuing staunch denials of the allegation that the Prince slept with Ms Roberts on three occasions between 1999 and 2002 in London, New York and on a private Caribbean island during an orgy.

The accusation is reportedly contained in a motion filed in a Florida court as part of a lawsuit over how federal prosecutors handled the case of Epstein, who was jailed for 18 months in 2008 for soliciting a minor for paid sex.

Sarah's comments came as reports surfaced claiming Epstein used "aggressive witness tampering" on employees who later avoided answering questions about sex claims relating to the Duke of York.

According to the Daily Telegraph, Epstein is said to have paid the legal fees of witnesses who have refused to answer direct questions about whether young girls were "provided for sex" to the Duke.

The newspaper reports that one invoked the Fifth Amendment and stayed silent when she was asked about the Duke of York.

And the Daily Mail reports that court papers allege that Epstein went to great lengths to stop some of the young girls he allegedly abused from speaking to the FBI.

He reportedly "tracked them down" and promised to "look after" them if they did not speak.

Prince Andrew has since flown back to Britain amid the controversy surrounding the claims but is expected to return to Switzerland in a few weeks to join prime ministers, business leaders and economists at Davos, the venue for the World Economic Forum's annual meeting.

The Duke of York with his accuser, Virginia Roberts, who has returned home after living in Australia

A royal aide was quoted by the Press Association as saying: "The civil case is an ongoing process that won't end any time soon. However, since 2012 the Duke has worked very hard to establish and refocus his working priorities on education, technology and enterprise and he will carry on with that work.

"It's fair to say that the Duke of York is nothing if not resilient. He will be keen to push on with the work he's been doing in recent years."

Ms Roberts, a US citizen, waived her anonymity in an interview with the Mail on Sunday in 2011, in which she claimed she had been sexually exploited by Epstein - a former friend of the Duke.

In the US court papers, she goes further and alleges that between 1999 and 2002 she "was forced to have sexual relations with this prince when she was a minor" in London, New York and on a private Caribbean island owned by Epstein.

The accusation is reportedly contained in a motion filed in a Florida court as part of a lawsuit over how federal prosecutors handled the case of Epstein, who was jailed for 18 months in 2008 for soliciting a minor for prostitution.

In a strongly-worded statement, a Buckingham Palace spokesman said: "It is emphatically denied that the Duke of York had any form of sexual contact or relationship with Virginia Roberts.

"The allegations made are false and without any foundation."

Additional reporting by PA