UK Prime Minister Keir Starmer faced mounting pressure to quit on Friday over his appointment of Peter Mandelson as envoy to Washington, after it emerged the veteran politician had failed security vetting.

The affair has haunted Starmer for months amid growing anger over Mandelson’s 2024 nomination to the top diplomatic post despite his close ties to late US sex offender Jeffrey Epstein.

Mandelson, a long-time insider with Starmer’s ruling Labour Party, has held multiple ministerial posts since the late 1990s – but has been dogged by repeated scandals throughout his career.

The government has blamed foreign ministry officials for the latest debacle, saying neither Starmer nor his foreign minister were told about Mandelson’s failed security check until this week.

The top civil servant in the foreign ministry, Olly Robbins, has now quit after Starmer “lost confidence in him” over the failure to tell him “about this decision”, senior minister Darren Jones said on Friday.

Foreign ministry officials made the decision to allow Mandelson’s appointment to proceed “against the recommendation of UK Security Vetting”, the government said on Thursday.