The Metropolitan Police has apologised to the Commons Speaker for revealing he was the source of a tip-off relating to the arrest of Lord Mandelson.
The force said it had "inadvertently" revealed information about why the ex-business secretary had been taken into custody on Monday.
Lawyers for Lord Mandelson had claimed the arrest was due to the "baseless" claim that he was preparing to flee the country for the British Virgin Islands.
Sky News understands officers had originally planned to interview him under caution, without arrest, next month.
Some media reports named the source of the flight risk claim as the Lord Speaker, Lord Forsyth.
But addressing the Commons before PMQs on Wednesday, Speaker Sir Lindsay Hoyle revealed it was him, saying he had done so "in good faith, as is my duty and responsibility".
A statement from the Met said it had since apologised to him "for inadvertently revealing information during an investigation into allegations of misconduct in public office".
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Lord Forsyth is to meet the Met on Thursday to ask how he was incorrectly named as the source.
Sky News understands he wants to know why the Met didn't correct the reporting and issue an apology. The Met has been approached for comment.
Meanwhile, the investigation into Lord Mandelson continues after he was bailed in the early hours of Tuesday.
The misconduct in public office probe relates to allegations he passed market-sensitive government information to Jeffrey Epstein when he was in Gordon Brown's government.
Lord Mandelson has repeatedly denied any wrongdoing.
(c) Sky News 2026: Met Police apologises to Commons Speaker over Lord Mandelson tip-off
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