The family of Virginia Giuffre have expressed their “deep disappointment” that Andrew Mountbatten-Windsor will not face a criminal investigation in the UK over allegations against him.

It was alleged that Mountbatten-Windsor had sex in London with a teenager who was trafficked, and then put pressure on his police protection officer to dig up dirt on her.

The Metropolitan police on Saturday said after weeks of review, it would not launch any formal criminal investigation into King Charles’s brother. Mountbatten-Windsor’s ties to the convicted child sex offender Jeffrey Epstein led to the stripping of his royal status.

His alleged victim, Virginia Giuffre, claimed in a 2021 US lawsuit that Andrew had sex with her after she had been trafficked by Epstein at a home in Belgravia, London, in 2001 when she was 17.

In a US lawsuit she said she was “lent out for sexual purposes” to the then Duke of York in London, and on two other occasions outside the United Kingdom.

Mountbatten-Windsor, 65, has always denied that claim and any other wrongdoing, and maintained his position when he paid money to settle the lawsuit in 2022.

The family of Giuffre said they were “deeply disappointed” by the force’s decision to drop the investigation “without explanation” and that they were not told this announcement was coming.

They said in a statement: “We emailed with a detective from the Metropolitan police yesterday, Friday, Dec 12th, who gave us no indication that this announcement was imminent.

“Indeed, he asked us if we had any evidence we would like to present; we had not yet replied.

“With the Epstein files about to be released by [the US] Congress since the passage of the Epstein Transparency Act, we are surprised that the Metropolitan police didn’t wait to see what further evidence might appear.

“While we have hailed the UK’s overall handling of the case of Andrew Mountbatten-Windsor previously, today we feel justice has not been served.

“We continue to challenge the system that protects abusers, especially as more evidence comes to light that can hold people accountable. Our sister Virginia, and all survivors, are owed this much.”

It is understood that on some of the former prince’s meetings with Epstein, a Met protection officer accompanied him, as he was entitled to police protection given his royal status.

On Saturday, the Met said no allegation against Mountbatten-Windsor would be the subject of any formal criminal investigation in the UK. That includes claims he asked his Met police protection officer to investigate Giuffre in 2011, after she had gone public with her claims against him.

Any criminal investigation would have involved the king’s brother being interviewed under criminal caution, if not arrested. The Met’s decision was reached without speaking to the former prince.

In a new statement, the Met commander Ella Marriott said the force had decided to stand by its previous decision. Marriott said: “In 2015, the Metropolitan police service received allegations relating to non-recent trafficking for sexual exploitation involving Jeffrey Epstein and Ghislaine Maxwell.

“These allegations primarily concerned events outside the United Kingdom, with one allegation of trafficking to central London in March 2001.

“Officers assessed all available evidence at the time, interviewed the complainant, Ms Virginia Giuffre as well as contacting several other potential victims. This did not result in any allegation of criminal conduct against any UK-based nationals.

“The MPS sought advice from the Crown Prosecution Service and liaised with US authorities, who were leading investigations into related matters involving US nationals. Following this legal advice, it was clear that any investigation into human trafficking would be largely focused on activities outside the UK and perpetrators based overseas.

“Officers therefore concluded, in consultation with the CPS, that other international authorities were best placed to progress these allegations. Officers maintained close liaison with the US and other relevant authorities throughout their investigation to ensure any UK matters could be identified and to consider any support requested.

“A decision was made in November 2016 not to proceed to a full criminal investigation. That decision was reviewed in August 2019 and again in 2021 and 2022; in each instance, the position remained unchanged, and Ms Giuffre and her legal representative were informed.”

The Met said there would be no criminal investigation into claims Mountbatten-Windsor tried to get his police protection officers to smear his accuser.

It is understood none of the protection officers at that time, who have been spoken to by Met investigators, supported claims that Mountbatten-Windsor asked them to find material that might undermine Giuffre.

Detectives examined the Met’s records dating back more than a decade to see if any officer searched for material on Giuffre. Some records no longer existed.

In October, the Mail on Sunday claimed an email showed Mountbatten-Windsor passed Giuffre’s date of birth and social security number to his bodyguard in 2011 and asked him to dig up dirt to smear his accuser.

On Saturday Marriott said: “This assessment has not revealed any additional evidence of criminal acts or misconduct.

“In the absence of any further information, we will be taking no further action. As with any other matter, should new and relevant information be brought to our attention, including in any information resulting from the release of material in the US, we will assess it.”

A former senior prosecutor said there could be enough reason to criminally investigate Mountbatten-Windsor for his alleged sexual attack on Giuffre.

Nick Vamos, the former head of special crime at the CPS, said: “If Ms Giuffre did not consent to sex, and Andrew did not reasonably believe that she consented to sex, then it would be rape. If it could be proved that Andrew knew that Giuffre had been trafficked then that would be compelling evidence that he could not have reasonably believed that Giuffre had the freedom to choose whether to consent.”

Giuffre is now dead, but her New York lawsuit said the British socialite Ghislaine Maxwell recruited her for Epstein’s sex trafficking enterprise. Maxwell is in a US prison.

In her 2021 civil lawsuit brought against the former prince in the southern district of New York, Giuffre said: “Prince Andrew committed sexual assault and battery upon plaintiff when she was 17 years old. As such, Prince Andrew is responsible for battery and intentional infliction of emotional distress pursuant to New York common law. The damage to plaintiff has been severe and lasting.

“Prince Andrew abused plaintiff on separate occasions when she was under the age of 18 years old. On one occasion, Prince Andrew sexually abused plaintiff in London at Maxwell’s home. During this encounter, Epstein, Maxwell, and Prince Andrew forced plaintiff, a child, to have sexual intercourse with Prince Andrew against her will.”

Giuffre also alleged the former prince had sex with her on two other occasions outside the UK. Giuffre’s sworn statement said: “During each of the aforementioned incidents, plaintiff was compelled by express or implied threats by Epstein, Maxwell, and/or Prince Andrew to engage in sexual acts with Prince Andrew, and feared death or physical injury to herself or another and other repercussions for disobeying Epstein, Maxwell, and Prince Andrew due to their powerful connections, wealth, and authority.

“Prince Andrew engaged in each of the aforementioned sexual acts with plaintiff at Epstein and Maxwell’s invitation, knowing that she was a sex-trafficking victim being forced to engage in sexual acts with him.

“During each of the aforementioned incidents, plaintiff did not consent to engaging in sexual acts with Prince Andrew. During each of the aforementioned incidents, Prince Andrew sexually abused plaintiff for the purpose of gratifying his sexual desires.”

Vamos said Giuffre’s book published posthumously this year could not be used as evidence, but her testimony for the New York lawsuit could be: “A sworn statement she had made in the past could be admissible such as her statement in the New York lawsuit. The book would probably not be.

“You would have to prove that she did not consent, had been trafficked, and Andrew knew that and thus could not reasonably believe she had freely consented.”

Mountbatten-Windsor has always denied Giuffre’s claim and any other wrongdoing.