The British Government hopes the Duke of York will agree to speak directly to the FBI over his links to Ghislaine Maxwell without the need for ministers to intervene, The Telegraph has learnt.
Home Secretary Priti Patel is facing a diplomatic quandary after US prosecutors submitted a formal request for the Duke of York to speak to them about claims Maxwell trafficked young women for sex for Jeffrey Epstein.
Their request was made through the filing of a Mutual Legal Assistance (MLA) to the Home Office, as part of an agreement allowing the US to seek help from the British authorities in a legal or criminal matter.
But it is now understood the British Government is in favour of the stand-off between the Duke and the FBI being sorted out between the two parties, rather than by any ministerial intervention under a MLA.
The Duke had a long friendship with Epstein and stayed at his homes, including Epstein's mansion in New York and his home in the US Virgin Islands.
Prosecutors believe he could have vital information as a witness rather than a suspect, although the Duke insists he never saw or suspected any wrongdoing in the times he stayed at Epstein's homes.
As a potential witness, the Duke cannot be compelled to talk to the FBI, but the matter threatens to become deeply embarrassing for the Home Office after the submission of the MLA.
Extradition expert Andrew Campbell-Tiech QC, head of Drystone Chambers, said: "I'm sure the Home Office would rather the two parties deal with it themselves without any ministerial involvement. The last thing they want is to find themselves caught between the Royal family on one side and the US authorities on the other. They do not want to navigate through that."
Maxwell is accused of lying about Epstein's sexual activities, including the recruitment of underage girls for sexual massages. The perjury allegations are the only charges brought against Maxwell to date that relate to a period of time when the Duke knew Epstein.
The more serious offences of child sex trafficking and grooming are alleged to have taken place between 1994 and 1997, two years before the Duke was introduced to Epstein.
The alleged offences against one of the victims took place in London between 1994 and 1995, when she was under the age of 18.
Campaign groups and lawyers representing victims of sex abuse have now called on the Metropolitan Police to mount their own investigation into the London allegations rather than just defer to US investigators.
Harriet Wistrich, a solicitor and founder and director of the Centre for Women's Justice, said: "If there are offences that took place in London and the Metropolitan Police's area then they should investigate them, if that is what the victims want."
Scotland Yard said it had liaised with other law enforcement organisations but had not received a formal request asking for assistance in connection with the allegations.
US prosecutors said they would "welcome" the Duke's testimony as part of the ongoing FBI investigation, with Audrey Strauss, acting US Attorney for the Southern District for New York, urging the Duke to come forward to be questioned.
The Duke's lawyers say they twice contacted the US Department of Justice in the past month but received no response.
A source close to the Duke's team said: "We've been in contact with the US Department of Justice saying we're willing to offer assistance. The Duke has indicated his intention to cooperate with the investigation and the ball is now in their court.
"There is still a dialogue going on and we are sure the Home Office would not want to intervene."
The Duke's legal problems deepened on Friday after a new lawsuit from one of Epstein's alleged victims was filed on Thursday.
The civil claim against Epstein's $630 million (£505 million) estate is being brought by Caroline Kaufman, now 26, who alleges that she was sexually abused by Epstein in 2010 when she was 17 at the financier's New York mansion. She claims she was raped while the Duke of York was visiting.
The Duke was pictured leaving the Upper East Side townhouse in 2010, two years after Epstein was convicted by a Florida state court of procuring an underage girl for prostitution.
The Duke claimed he had travelled to the US to cut ties with Epstein, who committed suicide last year in a new York cell while facing fresh charges.
The lawsuit does not accuse the Duke of wrongdoing or of being aware of the alleged attack.
He has previously said of Epstein, who died in prison last year: "At no stage during the limited time I spent with [Epstein] did I see, witness or suspect any behavior of the sort that subsequently led to his arrest and conviction."
Meanwhile, the prosecutor who has been at the heart of the tussle over getting the Duke to give his account to US investigators could this week reveal more about the situation.
Geoffrey Berman, who was controversially fired as US attorney for the Southern District of New York last month by the Trump administration, will appear at a congressional committee to answer questions.
Berman led the Maxwell investigation and publicly called for the Duke of York to speak to him a number of times, including claiming that the royal had been resisting the move.
Berman is due to spend hours giving testimony to the House Judiciary Committee next Thursday.
Congressmen could seek to better understand why prosecutors are so keen to talk to the Duke and the full details of his legal team's correspondence about giving an interview.
A spokesman for the prosecutors at the Southern District of New York declined to comment on the question of Mutual Legal Assistance.
The Home Office would not confirm or deny the existence of an MLA request.