Prince Andrew has provided “zero” cooperation with the Jeffrey Epstein sex trafficking inquiry, US prosecutors said on Monday, despite earlier promises to help investigations in any way possible.

Speaking outside Epstein’s Manhattan mansion, Geoffrey Berman, US attorney for the southern district of New York, said the agencies had contacted Andrew regarding an interview, but that he had not yet agreed to provide one.

It is understood that there will be no attempt to force Andrew to testify, leaving open the possibility that he will never answer prosecutors’ questions about his relationship with Epstein.

Prince Andrew, 59, stepped back from royal duties in November, following a widely-criticized interview with the BBC about his friendship with Epstein.

At the time, Andrew, said he was “willing to help any appropriate law enforcement agency with their investigations if required” over the ongoing US probe into Epstein – who was charged with sex-trafficking.

But at a press conference in New York City’s Upper East Side, Berman told reporters that requests had so far gone unanswered.

Federal prosecutors in the southern district of New York, along with the FBI, were seeking to interview Andrew as they probe into Epstein’s potential co-conspirators.

Buckingham Palace said it would not be commenting. The matter is being dealt with by Prince Andrew’s legal team.

Epstein was arrested in July 2019 and charged with sex trafficking girls as young as 14. He was found dead in a jail cell in August 2019, the medical examiner ruled his death to be suicide.

The wealthy financier once had a wealthy and influential circle of friends that included Donald Trump, Bill Clinton and Prince Andrew.

That network largely deserted Epstein after he pleaded guilty to procuring a person under the age of 18 for prostitution and was sentenced to 18 months in prison. Andrew, however, stayed at Epstein’s home in December 2010, months after he had been released from prison.

One of Epstein’s accusers in his July arrest, Virginia Giuffre, said she was instructed to have sex with Andrew in 2001, when she was 17 years old.

Prince Andrew told the BBC he had “no recollection” of meeting Giuffre, and said on the night the alleged sex occurred he was at a Pizza Express in Woking.

After Epstein’s death William Barr, the US attorney general, vowed that the federal sex-trafficking case into Epstein would continue. “Any co-conspirators should not rest easy,” Barr said at the time.

Andrew, the eighth in line to the throne, was effectively suspended from royal duties by Queen Elizabeth in the aftermath of his BBC interview. In a statement released in Andrew’s name, he said: “It has become clear to me over the last few days that the circumstances relating to my former association with Jeffrey Epstein has become a major disruption to my family’s work and the valuable work going on in the many organisations and charities that I am proud to support.

“Therefore, I have asked Her Majesty if I may step back from public duties for the foreseeable future, and she has given her permission.”

Before being asked about the Duke, Berman confirmed the investigation was looking at possible “conspirators” who worked with Epstein.

He added: “Jeffrey Epstein couldn’t have done what he did without the assistance of others, and I can assure you that the investigation is moving forward.”

Berman was speaking at an event to promote a new law that makes it easier for victims to sue over childhood abuse.

The Home Office declined to comment on whether there had been any formal US request to interview or even extradite Prince Andrew to the USA. Any request for extradition would normally go to the Home Office initially.

Scotland Yard has previously defended its decision to drop an investigation into claims of sex trafficking made against Epstein by Giuffre, who says she was forced to sleep with the Duke of York.

Prince Andrew has dropped out of public sight for most of the past few months but did appear alongside the Queen, his mother, at a church service in Norfolk earlier this month.

There have been unconfirmed reports of a downgrading of Andrew’s security since he no longer performs royal engagements. Unlike Prince Harry, he continues to use his HRH title.

A final decision is said to rest with the home secretary, Priti Patel, and the prime minister, Boris Johnson, after review by the Metropolitan police.

Andrew stood down from public duties within days of the BBC interview with the Newsnight anchor Emily Maitlis. He was accused of lacking empathy for Epstein’s victims and of failing to show regret over his friendship with the disgraced US financier.

During the interview he said he was prepared to give testimony under oath “if push came to shove and the legal advice was to do so”.

Andrew has said he did not see, witness or suspect any suspicious behaviour during his visits to Epstein’s homes in Florida, New York and the Caribbean.

• This article was amended on 29 January 2020. An earlier version stated that Prince Harry had not retained his HRH status. This has now been corrected.