British police have launched a formal criminal investigation into Peter Mandelson, a senior former cabinet minister and one-time ambassador to the United States, following revelations in newly released documents connected to the Epstein archive that suggest he may have shared sensitive government information with the late financier Jeffrey Epstein.

Metropolitan Police detectives confirmed they were reviewing reports of alleged misconduct in public office — an offence that carries a maximum life sentence — after the government referred material to law enforcement for assessment.

The files, released by the United States Department of Justice, include emails and correspondence from Mandelson during his tenure as business secretary under former prime ministers that appear to show him forwarding confidential communications and market-sensitive details to Epstein and maintaining a personal relationship after Epstein’s 2008 conviction for state charges in Florida.

In response to the emerging details, Mandelson announced his resignation from the House of Lords, relinquishing his lifetime parliamentary seat amid the intensifying scrutiny.

Prime Minister Keir Starmer, who dismissed Mandelson from his post as Britain’s envoy in Washington in September, has described the alleged conduct as deeply troubling, instructed officials to draft legislation that could strip Mandelson of his noble title, and supported limited public disclosure of documents related to the appointment and vetting process.

Starmer also agreed with King Charles III to remove Mandelson from the Privy Council on grounds that his actions brought the body’s reputation into disrepute.

The government has provided police with its assessment that the released files contain information on the global financial crisis and internal policy deliberations that should not have been shared outside secure official channels.

Legal experts and former senior officials have underscored the seriousness of a misconduct in public office investigation, cautioning that an inquiry does not equate to charges, but emphasising the potential ramifications if allegations are proved.

In parallel, political figures including former prime ministers and opposition leaders have condemned Mandelson’s conduct and called for full transparency over vetting procedures that allowed his ambassadorial appointment despite longstanding ties to Epstein.

The case has also prompted calls for related investigations into Mandelson’s earlier tenure as European Union trade commissioner and broader concerns about the handling of sensitive government material and ethical standards in public life.