US authorities have not made an official approach to the British government for permission to speak to Prince Andrew about his contacts with Jeffrey Epstein, Prime Minister Boris Johnson said.
US prosecutors want to question the British royal over his contacts with Epstein, who was awaiting trial on charges of trafficking minors when he died last August in a New York City federal prison.
However, they have said Prince Andrew had repeatedly evaded their requests for an interview, and reiterated their desire to speak to him after they arrested British socialite Ghislaine Maxwell yesterday, the former girlfriend and longtime associate of Epstein.
Lawyers for Prince Andrew, who met Epstein through his friendship with Ms Maxwell, say he has offered his help three times this year.
Asked what the response would be if US officials sought formal access to the prince, Mr Johnson said: "No such approach has been made. It's a matter for the royal family."
He added: "Everybody's sympathies are very much with the victims of Jeffrey Epstein but you wouldn't expect me to comment on matters affecting the royal family."
"The law must [be] carried out and the law must be observed," he told LBC radio.
London Mayor Sadiq Khan has called on the Duke to provide information to American authorities.
Also speaking on LBC radio, he said: "I think it's really important for those of us in positions of power and influence to lead by example.
"We shouldn't lose sight of who the victims are, they were children at the time - vulnerable children, young women - and it's really important that anybody who has information helps the FBI, and that includes Prince Andrew."
In June, then-US Attorney for Manhattan Geoffrey Berman said Prince Andrew had "sought to falsely portray himself to the public as eager and willing to cooperate" with their inquiry.
At the same time, a US law enforcement official confirmed to Reuters that US authorities investigating Epstein had sent the British government a formal request, known as a mutual legal assistance treaty (MLAT) submission, asking for access to the prince.
After Ms Maxwell was arrested and charged with luring underage girls for Epstein to sexually abuse, acting Manhattan US Attorney Audrey Strauss said: "We would welcome Prince Andrew coming in to talk with us."
Prince Andrew's legal team have accused the US Department of Justice (DOJ) of seeking publicity rather than his help, rejecting accusations he had offered "zero cooperation".
"The Duke's team remains bewildered given that we have twice communicated with the DOJ in the last month, and to-date, we have had no response," a source close to Prince Andrew's team said in response to Ms Strauss's remarks.
A spokesperson for the Metropolitan Police Service has told RTÉ News that it has "nothing to add" following the arrest of Ghislaine Maxwell in the United States.
It pointed to a statement from November 2019, when Met Police received an allegation of non-recent trafficking for sexual exploitation against Jeffrey Epstein and a British woman.
However, police decided did not proceed to a full criminal investigation.
The statement said that following legal advice "it was clear that any investigation into human trafficking would be largely focused on activities and relationships outside the UK" and "the MPS was not the appropriate authority to conduct enquiries in these circumstances".
US prosecutors allege that acts of abuse took place at Ms Maxwell's residence in London.
Lawyer Spencer Coogan said his clients were "relieved" that Ms Maxwell had been arrested, and urged Prince Andrew to speak out about what he witnesses while visiting Epstein's properties in New York, Palm Beach and the Virgin Islands.
Speaking on BBC Radio 4, he said: "On behalf of the victims, we have continuously asked him to step forward ... he has been hiding behind not only the royal family, but his attorneys."
Additional reporting PA, Jackie Fox