Peter Mandelson failed his security vetting before being appointed as ambassador to the US, however No 10 has insisted that the Kier Starmer knew nothing about this.

Security officials rejected his clearance before the disgraced peer was dispatched to Washington last year.

It emerged on Thursday (April 16) that officials in the Foreign Office overruled the decision so Mandelson's appointment could go ahead, The Mirror reports. Downing Street said in a statement that the PM was unaware until this week, and had planned to update the Commons.

The extraordinary chain of events, first reported by The Guardian, has been met with anger by MPs with the Foreign Office facing calls to come clean.

Speaking to reporters in Washington DC, Chancellor Rachel Reeves said: “I didn’t know anything about the vetting process. I’m the Chancellor, I’m not the Foreign Secretary, and I’m not 10 Downing Street, so I can’t give you any more information on that.”

A government spokesman said no ministers were aware, pointing the finger at department mandarins. In a statement No10 said: “The security vetting process for Peter Mandelson was sponsored by the FCDO.

WASHINGTON, DC - FEBRUARY 26: British Prime Minister Keir Starmer (R) talks with Britain's ambassador to the United States Peter Mandelson during a welcome reception at the ambassador's residence on February 26, 2025 in Washington, DC.(Image: Carl Court/Getty Images)

"The decision to grant Developed Vetting to Peter Mandelson against the recommendation of UK Security Vetting was taken by officials in the FCDO. Neither the Prime Minister, nor any Government Minister, was aware that Peter Mandelson was granted Developed Vetting against the advice of UK Security Vetting until earlier this week.

“Once the Prime Minister was informed he immediately instructed officials to establish the facts about why the Developed Vetting was granted, in order to enact plans to update the House of Commons."

Mr Starmer has vowed to be transparent, and the Government is committed to releasing all documents relating to Mandelson's appointment. In a landmark vote forced by the Tories, MPs backed a humble address demanding the files are released.