Britain's Prince Andrew on Monday hit back at claims he had failed to cooperate with US authorities investigating the late sex offender Jeffrey Epstein.

US lawyers have claimed that Queen Elizabeth II's second son refused to help in the case, which centres around lurid sex trafficking claims against the multi-millionaire financier.

The 60-year-old senior royal publicly defended his friendship with Epstein in a BBC television interview last year, prompting outrage from his victims, and leading him to quit frontline royal duties.

But Andrew's lawyers, Blackfords, said in a statement that claims he had stonewalled investigators were untrue, and accused the US Department of Justice (DoJ) of chasing headlines.

"The Duke of York has on at least three occasions this year offered his assistance as a witness to the DoJ," the statement said.

"Unfortunately, the DoJ has reacted to the first two offers by breaching their own confidentiality rules and claiming that the Duke has offered zero co-operation.

"In doing so, they are perhaps seeking publicity rather than accepting the assistance proffered."

Andrew, a former Royal Navy helicopter pilot who as a younger man had a reputation as a playboy prince, is accused of having sexual relations with one woman when she was 17 -- an allegation he has vehemently denied.

The woman, Virginia Giuffre, alleges she was trafficked under-age to have sex with friends of Epstein, who was 66 when he killed himself in a New York jail in August last year.

Andrew's lawyers said they had upheld their commitment to confidentiality but said they were forced to go public "in view of misleading media briefings" from the United States.

US investigators had been looking into Epstein's affairs for more than 16 years but only requested the prince's help on January 2 this year, they said.

"Importantly, the DoJ advised us that the Duke is not and has never been a 'target' of their criminal investigations into Epstein and that they sought his confidential, voluntary cooperation.

"In the course of these discussions, we asked the DoJ to confirm that our co-operation and any interview arrangements would remain confidential, in accordance with the ordinary rules that apply to voluntary co-operation with the DoJ," the statement said.

"We were given an unequivocal assurance that our discussions and the interview process would remain confidential."

The lawyers pointed to two claims from New York attorney Geoffrey Berman on January 27 and March 9 that the duke was refusing to cooperate, leading to "misleading" media reports.

"These statements were inaccurate, and they should not have been made," Andrew's lawyers added, accusing the DoJ of treating their client "by a lower standard" than anyone else.

The Sun newspaper on Monday reported that the DoJ had submitted a mutual legal assistance request to Britain's interior ministry to force the prince to give a statement.

His lawyers said that would be "disappointing" given his willingness to do provide a written statement voluntarily.