The "lurid" details of sex allegations made against Prince Andrew should be struck from court records, a US judge says.

Florida district Judge Kenneth Marra ruled the allegations made against the Duke of York had no place in a civil case against billionaire financier Jeffrey Epstein.

Two women — referred to in court documents as Jane Doe 3 and Jane Doe 4 — are trying to join the civil suit dating back to 2008.

Jane Doe 3 alleged she was "forced to have sexual relations" with Prince Andrew in London, New York and the Caribbean at the behest of Epstein when she was 17.

She claimed Epstein, a former friend of the 54-year-old prince, kept her as a "sex slave."

The civil suit the two women tried to join accuses federal prosecutors of cutting a plea-bargain deal with Epstein without consulting his victims, in violation of the US Crime Victims Rights' Act.

But Judge Marra said the claims were not needed and ordered them stricken from the record.

"At this juncture in the proceedings, these lurid details are unnecessary to the determination of whether Jane Doe 3 and Jane Doe 4 should be permitted to join petitioners' claim that the government violated their rights," he wrote in a 10-page ruling.

The judge went on to say that the pair should not be added to the original case, but could be called as witnesses at trial.

Buckingham Palace has repeatedly and strongly denied the allegations against Andrew, calling them "false and without foundation".

In January, the Prince said he wished to "reiterate and reaffirm" the denials.

In 2008, Epstein was sentenced to 18 months in prison after pleading guilty to a single Florida state charge of soliciting prostitution. He remains a registered sex offender.

ABC/AFP