Lord Peter Mandelson has been asked to give evidence to the US Congress over his relationship with the paedophile financier Jeffrey Epstein.

A letter from two Democrat members of the House of Representatives called on the former British ambassador to Washington DC to answer questions from the House Oversight Committee as part of their probe into Epstein.

Lord Mandelson’s links with Epstein have led to calls for Sir Keir Starmer to stand down as Prime Minister.

Critics have questioned the Prime Minister’s judgment in appointing the peer as US ambassador, which is considered the most prestigious posting in British diplomacy.

The letter to Lord Mandelson, signed by representatives Robert Garcia and Suhas Subramanyam, 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.”

The letter also said: “Numerous pieces of evidence have come to light demonstrating your close ties to Jeffrey Epstein over the span of multiple years.”

Among the evidence, it listed Lord Mandelson’s “handwritten note” in a 50th birthday book for Epstein in which he described the financier as his “best pal”.

It also pointed to the peer’s stay at the financier’s New York apartment in 2009, while Epstein was serving an 18-month sentence for soliciting prostitution and soliciting a minor, as well as photographs of Lord Mandelson in his underwear in the latest Department of Justice release.

Lord Mandelson was given a deadline of February 27 to respond to the two US politicians’ letter “due to the urgency and gravity of this matter”.