Lord Peter Mandelson’s lawyers have said the former cabinet minister was arrested after what they said was a “baseless suggestion that he was planning to leave the country”.

The ex-Labour grandee was released on bail in the early hours of Tuesday morning after his arrest on suspicion of misconduct in public office, which followed claims he leaked sensitive UK government information to the paedophile financier Jeffrey Epstein.

His law firm Mishcon de Reya said it has asked the Metropolitan Police “for the evidence relied upon to justify the arrest”.

It also said there had been an agreement with police that the UK’s former ambassador to Washington would be interviewed on a voluntary basis next month, but that had been hastily overturned amid a suggestion that he was planning to move abroad permanently.

In a statement released on Tuesday evening, the firm said: “Peter Mandelson was arrested yesterday despite an agreement with the police that he would attend an interview next month on a voluntary basis.

“The arrest was prompted by a baseless suggestion that he was planning to leave the country and take up permanent residence abroad.

“There is absolutely no truth whatsoever in any such suggestion. We have asked the MPS for the evidence relied upon to justify the arrest. Peter Mandelson’s overriding priority is to cooperate with the police investigation, as he has done throughout this process, and to clear his name.”

Earlier, the former BBC journalist Emily Maitlis said on her News Agents podcast that she had seen a message she said had been sent by Mandelson to a journalist colleague at 4am on Tuesday, hours after he was released from police custody.

Ms Maitlis said that the message talked about the previous agreement between the police and his legal team to have a voluntary interview in early March, and added that the police had arrested him because of information that he was about to leave for the British Virgin Islands and take up permanent residence abroad.

Ms Maitlis said the message ended: “I need hardly say complete fiction. The police were told only today that they had to improvise an arrest. The question is, who or what is behind this?”

Mandelson has been accused of passing the information onto Epstein during his time as business secretary in Gordon Brown’s govermment.

As part of the so-called Epstein files, emails from 2009 appeared to show Lord Mandelson had passed on an assessment by one of Brown’s adviser of potential policy measures including an “asset sales plan”.

The emails released by the US also appeared to have been sent to Epstein after he became a convicted sex offender.

The Metropolitan Police declined to comment.

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