Peter Mandelson has been asked to testify to the US Congress over his relationship with the convicted sex offender Jeffrey Epstein.

Robert Garcia, ranking member of the committee on oversight and government reform, and congressman Suhas Subramanyam have written to Mandelson requesting he be questioned as part of the investigation into Epstein.

The letter said: “While you no longer serve as British ambassador to the United States and have stepped down from the House of Lords, it is clear that you possessed extensive social and business ties to Jeffrey Epstein and hold critical information pertaining to our investigation of Epstein’s operations.

“Given the appalling allegations regarding Epstein’s conduct, we request that you make yourself available for a transcribed interview with Committee staff regarding the crimes of Jeffrey Epstein and his co-conspirators.”

In the letter, the members point out instances where Mandelson was photographed or mentioned in the 3.5m Epstein files released in the past fortnight.

The former UK ambassador to the US has been given until the end of the month to respond.

Mandelson is also being investigated by the Metropolitan police for alleged misconduct in a public office after allegations that he passed market-sensitive information to Epstein when he was business secretary in Gordon Brown’s government in 2009.

Officers have searched two properties connected to the former member of the House of Lords as part of its investigation. Mandelson has denied any criminal wrongdoing.

Garcia and Subramanyam made a similar request to Andrew Mountbatten-Windsor to testify last year. Andrew has consistently denied any wrongdoing.

The former prince failed to respond to an interview request from the committee in November, prompting Keir Starmer to say those with “relevant information” should share it.

Mandelson resigned from the House of Lords and relinquished his membership of the Labour party earlier this month over his links to the late convicted child sex offender Epstein.

The former cabinet minister was sacked as US ambassador in September because of his past connections to the disgraced financier.