A criminal investigation has been launched into Lord Mandelson amid allegations he passed market-sensitive information to paedophile financier Jeffrey Epstein.
Met Police Commander Ella Marriott confirmed the force "has now launched an investigation into a 72-year-old man, a former Government Minister, for misconduct in public office offences".
It comes hours after the Lord Speaker confirmed Mandelson will step down from the House of Lords following fresh allegations concerning his relationship and dealings with Jeffrey Epstein.
Number 10 said they had passed material to the police after an initial review of documents released as part of the so-called Epstein files found they contained “likely market-sensitive information” and official handling safeguards had been “compromised”.
On Tuesday evening, a government spokesperson confirmed they will "provide whatever support and assistance the police need" in their investigation.
Earlier, former prime minister Gordon Brown said that he had written to Met Police Commissioner Sir Mark Rowley “with information relevant to his investigation of Lord Mandelson’s disclosure of market sensitive and confidential government information” to Jeffrey Epstein.
Mandelson has insisted Epstein’s money did not influence his actions in government.
He will formally retire from the House of Lords on February 4, the newly-installed Lord Speaker Lord Forsyth of Drumlean said.
A Downing Street spokesperson said: “It is right that Peter Mandelson will no longer be a member of the House of Lords.
“As the prime minister said this morning, Peter Mandelson let his country down.”
Speaking exclusively to ITV News on Tuesday, Foreign Secretary Yvette Cooper said the revelations have been "truly shocking".
Cooper sacked Mandelson as US ambassador in September, and was in government with him during the period over which he allegedly forwarded emails on to Epstein.
She said: "I removed Peter Mandelson as ambassador to the US very shortly after being appointed as foreign secretary.
"There’s clearly been a lot of information that just was not known and these revelations, for me, as someone who was in the Treasury at the time of the financial crisis, I find truly shocking."
Despite resigning, Mandelson will keep his title as a Lord.
This is because a life peerage cannot be relinquished – an Act of Parliament is needed to do that.
A law change to remove peerages last happened more than 100 years ago, when the Titles Deprivation Act 1917 (TDA) was created after the First World War to remove peerages from "enemies" of the UK.
The prime minister’s official spokesman said Starmer opened Tuesday’s Cabinet meeting by saying he was “appalled by the information that had emerged over the weekend in the Epstein files”.
“He said the alleged passing-on of emails of highly sensitive government business was disgraceful, adding that he was not reassured that the totality of information had yet emerged,” the spokesman said.
