Prince Andrew has been formally asked to respond to allegations by a woman who claims she was made to have under-age sex with him.

A letter addressed to the Prince at Buckingham Palace has been filed by lawyers acting on behalf of Virginia Roberts.

The document, filed on Wednesday in a Florida court, asks him to take part in a two-hour interview under oath.

Ms Roberts, who is referred to in court as Jane Doe No 3, claims when she was 17 she was forced to have sex with Prince Andrew by his friend Jeffrey Epstein - a financier and now convicted sex offender.

The Duke, who is not a party to the proceedings, strenuously denies the claims.

The letter, dated 14 January, said: "This letter is a formal request ... to interview you, under oath, regarding interactions that you had with Jane Doe No 3 beginning in approximately early 2001. Jane Doe No 3 was then 17 years old.

"The interview could be conducted at a time and place of your choosing, and with your co-operation, I believe the interview could be completed in two hours or less."

The Prince is expected to publicly deny the allegations when he hosts an event at the World Economic Forum in Davos later.

He is due to speak at around 5.30pm.