The US has demanded that the UK's Prince Andrew be handed over to American police to be questioned about his links to late financier and sex offender Jeffrey Epstein, according to media reports.
The US' Department of Justice (DoJ) has formally told the UK government that the Duke of York was now part of a criminal investigation, the Metro newspaper said in a report on Sunday.
The Duke, 60, has strongly denied any wrongdoing but has not faced questions from US prosecutors.
Now, the US appears to have bypassed Buckingham Palace by filing a "mutual legal assistance" request to the Home Office last month, The Sun newspaper has claimed.
Such requests are only used in criminal cases under a legal treaty with the UK. That could force the Royal to appear as a witness in a UK court within months either voluntarily, or by being summoned from the DoJ.
A source told The Sun: "It's a huge statement of intent from the US and it moves Andrew into the realms of a criminal investigation. It's also frankly a diplomatic nightmare."
A source close to the Duke's legal team told the Metro newspaper on Sunday evening: "Legal discussions with the DoJ are subject to strict confidentiality rules, as set out in their own guidelines.
"We have chosen to abide by both the letter and the spirit of these rules, which is why we have made no comment about anything related to the DoJ during the course of this year. We believe in playing straight bat."
A Buckingham Palace told Metro newspaper that the development was a matter for Prince Andrew's legal team.
The UK royal was removed from public duties last November following allegations he had slept with a teenager who was trafficked by Epstein, who was found dead in his New York jail cell while awaiting trial last August.
The victim, Virginia Giuffre, has claimed she was trafficked when she was 17 and was forced into sexual encounters with the Prince in London, New York and on a private Caribbean island owned by Epstein.
Prince Andrew has denied any wrongdoing and last year, he had indicated his willingness to cooperate with investigators.
Epstein was found dead in his New York jail cell while awaiting trial last August. His death was subsequently ruled a suicide.
( With inputs from IANS )