British ministers face calls to act after US authorities secretly flew out of the UK a diplomat accused of possessing indecent images of children.

US officials reportedly raided the diplomat’s London flat in August before taking him to an American airbase and flying him out of the country, without warning the Metropolitan police.

American personnel have no powers of arrest in Britain, and there was no formal request for the man to be extradited.

UK ministers are understood to be in contact with the US embassy over the incident, which could further strain relations between London and Washington.

Elements of the case echo that of an American fighter pilot, first reported in the Guardian, who avoided being tried under English law for strangling a woman in Cambridge while off-duty. Capt Jacob Wulfson was tried by court martial at a US airbase and jailed for six months after being convicted of strangulation. He was acquitted of charges of sexual assault and aggravated sexual contact.

In a letter to the justice secretary, Alex Norris, his Conservative counterpart, Nick Timothy, said he was concerned US actions represented “a cover-up” and that the diplomat may have committed offences in the UK. “If this is the case, the diplomat should face trial in an English court.”

Timothy said the incident was part of a “concerning pattern” of US authorities prosecuting American service personnel accused of offences against British civilians while stationed in the UK.

Citing the Wulfson case, he wrote: “These cases should have been investigated by the English police and prosecuted in our courts. I ask you to urgently explain what action you are taking to address this, and what will be done to ensure the accused diplomat faces a proper investigation in this country.”

The diplomat’s case has also been likened to that of the US state department employee Anne Sacoolas, who caused the death of the teenager Harry Dunn in a car crash in 2019. Sacoolas was able to leave the country shortly after the fatal collision when the US asserted diplomatic immunity on her behalf.

She eventually pleaded guilty to causing death by careless driving at a virtual high-court hearing in December 2022, and was sentenced to eight months in prison, suspended for a year.

A UK government spokesperson declined to comment because of the ongoing US investigation but said Britain expects all foreign diplomats to obey the law while in the UK, “in the same way we expect all UK diplomats to do so when posted overseas”.

A spokesperson for the US embassy said it was “aware of allegations” concerning one of its staff and expected “all personnel to adhere to the highest standards of conduct”.

The spokesperson said: “We quickly informed UK law enforcement and took swift action, and we will continue to work closely with our law enforcement partners regarding these allegations.

“The individual in question has been reassigned to the United States in conjunction with an ongoing investigation. The embassy has informed British authorities of the case.”

A US state department spokesperson declined to discuss the specifics of the case, adding: “We take these allegations seriously.”

A Met police spokesperson said: “On Tuesday 25 August, US authorities made us aware of an investigation they are conducting into suspected offences in London relating to indecent images of children. We continue to liaise with them regarding this matter.”