The European Union has opened a formal investigation into former British minister Peter Mandelson over suspected fraud, corruption, or serious misconduct during his time as EU trade commissioner, officials confirmed on Friday.

The probe is being led by the European Anti-Fraud Office (OLAF), which is examining whether any wrongdoing occurred between 2004 and 2008, when Mandelson held one of the bloc’s most powerful economic portfolios.

Investigators are understood to be reviewing material linked to the so-called Epstein files, though it remains unclear whether the inquiry centres on a specific allegation or a broader pattern of conduct.

The development adds to mounting legal pressure on Mandelson, who is already under criminal investigation in the UK. Earlier this year, Metropolitan Police Service officers questioned him over allegations that he leaked sensitive government information to disgraced financier Jeffrey Epstein while serving in government under Gordon Brown.

Separately, claims raised in Parliament have drawn attention to Mandelson’s past relationship with Russian oligarch Oleg Deripaska. Conservative MP David Davis has alleged that Mandelson made trade decisions benefiting Deripaska’s business interests and failed to disclose key details about their relationship.

Davis told MPs that Mandelson had spent weekends with Deripaska during his time in Brussels, suggesting gaps in oversight of commissioners’ activities.

OLAF confirmed only that an investigation is under way and declined to comment further. Mandelson has not publicly responded to the latest development.