Lord Mandelson has been released on police bail following his arrest on suspicion of misconduct in public office, the Metropolitan Police confirmed.
The 72-year-old former Labour minister, who previously served as EU Trade Commissioner and Business Secretary, was released pending further investigation into the allegations.
As reported earlier, Mandelson's arrest sent shockwaves through Westminster given his prominent role in New Labour and continued influence in political circles. The veteran politician has maintained a significant public profile since leaving frontline politics, including his recent appointment as the UK's ambassador to the United States.
The Metropolitan Police have not disclosed specific details about the nature of the misconduct allegations, stating only that inquiries are continuing. Under standard procedure, Mandelson will be required to report back to police at a specified date while the investigation proceeds.
The development marks the latest chapter in what has become a significant political story, with implications potentially extending beyond Mandelson's current ambassadorial role.