The Metropolitan Police has apologised to the Commons Speaker for "inadvertently revealing" he was the source of information relating to Lord Mandelson's arrest on Monday.

It comes after Sir Lindsay Hoyle confirmed he had passed on information to the force suggesting the peer could be a flight risk.

Lord Mandelson's lawyers have complained about the Met's decision to detain him as part of its probe into misconduct in public office allegations.

They say he had agreed to an interview next month, and the decision to take him into custody was prompted by a "baseless" suggestion he was planning to "take up permanent residence abroad".

The BBC understands that Lord Mandelson's lawyers were twice told by the police that information about his alleged travel plans had been passed on by Lord Forsyth, the Speaker of the House of Lords.

On Tuesday evening, Lord Forsyth denied any involvement after he was initially reported as the source of the referral, calling the suggestion "entirely false and without foundation".

On Wednesday, The Times then reported the information had in fact been shared by Sir Lindsay. Shortly afterwards, the Commons Speaker made a statement to MPs confirming he had given "relevant" information to the force.

He told MPs he had done this "in good faith", considering it to be his "duty and responsibility".

"It is regrettable this rapidly ended in the media," he added.

He did not provide any details, but the BBC understands Sir Lindsay passed on information he received in the British Virgin Islands during a visit last week that Lord Mandelson was planning to travel there.

Senior officers from the Met met Sir Lindsay on Wednesday to explain the situation, which is regarded by the force as a serious breach of protocol.

A spokesperson for the force said: "The Met has apologised to the Speaker of the House of Commons this afternoon for inadvertently revealing information during an investigation into allegations of misconduct in public office."

The BBC understands the Speaker of the House of Lords has not yet received an apology from the Metropolitan Police.

Lords sources said Lord Forsyth had arranged an urgent meeting with the Metropolitan Police on Thursday and was expected to receive clarification about how his name came to be mentioned.

The sources said he wanted to know why, when the media was widely reporting erroneous information attributed to him, he was not contacted about the issue and the record was not corrected.

Lord Mandelson's lawyers Mishcon de Reya have written to the Met asking what information and evidence they based their decision to arrest their client on.

The force is understood to have conducted its own assessment of the credibility of the information passed on by Sir Lindsay before deciding to arrest Lord Mandelson on Monday afternoon.

The former Labour minister was taken to Wandsworth police station in London for interview, before later being released on bail pending further investigation. It is understood he surrendered his passport as one of his bail conditions.

It comes after the force launched an investigation earlier this month over allegations that, while he was serving as a minister, Lord Mandelson had passed on market-sensitive government information to the late convicted sex offender Jeffrey Epstein.

The BBC understands that Lord Mandelson's position is he has not acted in any way criminally and that he was not motivated by financial gain. Lawyers for the peer say he intends to co-operate with police to "clear his name".

Lord Mandelson became the British ambassador to the US in February 2025 but was sacked in September after Downing Street said new information about the depth of his relationship with Epstein had emerged.

The allegations against Lord Mandelson surfaced after the US Department of Justice released a tranche of documents last month, including emails between him and Epstein.