A US judge ruled Wednesday that a sexual assault lawsuit brought against Prince Andrew can move forward, piling pressure on the royal and causing further embarrassment for the British monarchy.

New York judge Lewis Kaplan said he "denied in all respects" Andrew's motion to dismiss the civil complaint by accuser Virginia Giuffre, who says the prince abused her when she was 17.

Giuffre alleges that late disgraced financier Jeffrey Epstein lent her out for sex with his wealthy and powerful associates, including to Andrew, an allegation that Queen Elizabeth II's second son has repeatedly and strenuously denied.

Andrew's lawyers had last week urged Kaplan to throw out the suit, citing a settlement that Giuffre signed in 2009 with Epstein.

Andrew's attorney Andrew Brettler said Giuffre had "waived her rights" to sue other defendants in relation to alleged sex crimes committed by Epstein.

Prince Andrew has vehemently denied claims he had sex with Virginia Giuffre, and said he has no recollection of meeting her
Prince Andrew has vehemently denied claims he had sex with Virginia Giuffre, and said he has no recollection of meeting her AFP / JOHN THYS

But Kaplan said in his 46-page decision that the agreement was "riddled with drafting problems and ambiguities."

"The parties have articulated at least two reasonable interpretations of the critical language. The agreement therefore is ambiguous," he wrote.

The deal made public for the first time by a New York court this month showed that Giuffre agreed to drop a civil claim against Epstein for $500,000.

The settlement contained a provision purporting to protect "other potential defendants" from being sued related to alleged sexual abuse committed by Epstein, who killed himself in jail in 2019.

The agreement mentioned no names, but Andrew's legal team argued that it covered the royal.

Ghislaine Maxwell and Jeffrey Epstein in a photo entered into evidence at her sex crimes trial
Ghislaine Maxwell and Jeffrey Epstein in a photo entered into evidence at her sex crimes trial US District Court for the Southern District of New York via AFP / Handout

Kaplan said, though, that it could not be determined that the agreement was intended "to benefit Prince Andrew" or "others comparable to him."

The judge also noted that Andrew was "not a party to the agreement between Epstein and Ms. Giuffre."

"As a very general matter, the only persons who can enforce a provision of a contract are parties to that contract -- the people who agreed to it," he wrote.

Giuffre sued the prince for unspecified damages last year, alleging he sexually assaulted her in 2001 when she was a minor under US law.

This photo combination shows Britain's Prince Andrew and Virginia Giuffre, a woman who has accused him of wrongdoing in a sexual assault case that a US judge has allowed to go ahead
This photo combination shows Britain's Prince Andrew and Virginia Giuffre, a woman who has accused him of wrongdoing in a sexual assault case that a US judge has allowed to go ahead POOL via AFP / Steve Parsons

She says Andrew assaulted her at Epstein's home in New York, and on Epstein's private island in the US Virgin Islands.

Giuffre alleges the prince also sexually abused her at the London home of Ghislaine Maxwell, who in December was found guilty of sex trafficking minors for Epstein.

The 61-year-old Andrew has not been criminally charged.

Kaplan noted that he wasn't ruling on whether or not Giuffre's allegations were true.

"The law prohibits the court from considering at this stage of the proceedings defendant's efforts to cast doubt on the truth of Ms. Giuffre's allegations, even though his efforts would be permissible at trial," said the judge.

The case could go before a jury trial in the latter half of this year if Giuffre and Andrew are unable to reach a settlement.

Former New York attorney Richard Signorelli described the ruling as "devastating" for Andrew.

"He's facing very serious consequences," Signorelli told AFP, adding that paying Giuffre off could "potentially be very costly."

Giuffre's lawyer David Boies said she was "pleased" that "evidence will now be taken concerning her claims against him."

"She looks forward to a judicial determination of the merits of those claims," he said in a statement.

Andrew's lawyers did not respond to request for comment.

The prince has rarely been seen in public since he was forced to quit the royal frontline in 2019 for failing to distance himself from Epstein, who killed himself in prison that year while awaiting trial on sex trafficking charges.

In a disastrous 2019 interview with the BBC, Andrew said he had "no recollection of ever meeting" Giuffre.

He denied her claim that they had shared a sweaty dance at a London nightclub, saying that at the time he could not sweat due to a condition related to having fought in the 1982 Falklands War.

Giuffre's lawyers recently demanded that Andrew hand over medical records proving that he is unable to sweat.

Andrew's legal team has accused Giuffre of seeking to profit from a "baseless lawsuit."