Lawyers for the woman accusing Prince Andrew of sexual assault are seeking testimony from two people in the UK, according to court documents
Virginia Giuffres legal team want Robert Olney, the princes former assistant to provide a statement.
They also want one from a woman who says she saw the royal in a London club with a young girl around the time Ms Giuffre claims she was abused in 2001.
Prince Andrew has consistently denied the claims in the US civil case.
The 61-year-old, the Queens second son, this week failed in his attempt to have the case dismissed.
Judge Lewis Kaplan, who is hearing the case in New York, has asked for witnesses evidence to be taken by lawyers by 14 July and said a trial could take place in court later this year.
Ms Giuffre, now 38, claims the late financier Jeffrey Epstein trafficked her to have sex with men, including Prince Andrew when she was 17 - a minor under US law.
In letters submitted to the Royal Courts of Justice in London, her lawyer David Boies has requested two individuals in the UK provide evidence.
Seeking testimony from Mr Olney, who is the princes former equerry, the letter says Ms Giuffre has reason to believe that he has relevant information about Prince Andrewss relationship with convicted child sex offender Epstein.
This is because Mr Olneys name appears in publicly-available copies of Epsteins phone book, lawyers say.
The other letter seeks testimony from Shukri Walker.
The documents say Ms Walker has stated in the press that she was a potential witness to Prince Andrews presence at Tramp around the time Ms Giuffre says the royal abused her in London after visiting the club. They note Prince Andrew has denied being at Tramp on the night in question or having ever met Ms Giuffre.
The development comes after Buckingham Palace announced on Thursday that Prince Andrews military titles and royal patronages have been returned to the Queen.
"The Duke of York will continue not to undertake any public duties and is defending this case as a private citizen," the palace said in a statement.