British Ambassador to the United States Peter Mandelson listens as US President Donald Trump (not pictured) announces a trade agreement between the United States and the United Kingdom in the Oval Office of the White House in Washington, DC, USA, 08 May 2025. EPA/BONNIE CASH / POOL 
By Alistair Smout and Paul Sandle
London's Metropolitan Police previously said they were reviewing reports about alleged misconduct in public office but declined to comment on the launch of the investigation.
The reports of an investigation emerged after Prime Minister Keir Starmer's government handed material to the police to investigate whether Mandelson leaked information to Epstein during the financial crash.
Starmer told his ministers on Tuesday that Mandelson's alleged leaks to Epstein were "disgraceful." A few hours later, Mandelson said he would retire from parliament's upper house, the House of Lords.
Mandelson, a major player in the Labour governments of Tony Blair and Gordon Brown more than two decades ago, is facing possible criminal charges after emails released by the U.S. as part of the Epstein investigation suggested he had leaked confidential government documents to the financier.
The Times newspaper, citing a government source, said officers were expected to interview Mandelson and take statements from senior Labour figures, including Brown.
The emails suggest that in 2009, Mandelson sent Epstein a memo written for then-Prime Minister Brown about possible UK asset sales and tax changes, and in 2010 gave Epstein advance notice of a 500-billion-euro ($590 billion) bailout by the European Union.
STARMER'S GOVERNMENT TO COOPERATE WITH THE POLICE
Mandelson, 72, was fired from his ambassadorial role in September, seven months after being appointed, after documents emerged showing he had remained close to Epstein for much longer than he had previously acknowledged.
In one message, he appeared to tell Epstein that his earlier conviction, for procuring a child for prostitution, was wrong and he should fight for early release.
On Tuesday, Starmer told his cabinet that his government would cooperate with the police in any inquiries they carried out, adding he was not reassured that the totality of the information had yet emerged, according to his spokesperson.
His comments marked his strongest condemnation yet of the man he appointed ambassador to Washington last year despite his known association with Epstein, who committed suicide in prison in 2019.
"The prime minister said he was appalled by the information that had emerged over the weekend in the Epstein files," his spokesperson said.
Late on Sunday, Mandelson resigned from the Labour Party to prevent "further embarrassment", after a new release of millions of documents exposed details of his closeness to Epstein, including suggestions of payments to Mandelson and his husband.
The scandal has sparked concerns about Starmer's decision to appoint Mandelson as ambassador instead of a career diplomat, a decision advocated by his chief of staff, Morgan McSweeney.
Labour lawmaker Clive Efford, speaking in parliament on Monday, said the "key question here is who advised the prime minister?"
MANDELSON: NO RECOLLECTION OF EPSTEIN PAYMENTS
Mandelson has not responded to requests about the allegations. A spokesperson, however, has said Mandelson had no recollection of financial payments, totalling $75,000, from Epstein, as suggested by other emails and media reports.
In an interview with the Times conducted late last month and published on Tuesday, Mandelson said Epstein had been a "master manipulator." He added: "I've had a lot of bad luck, no doubt some of it of my own making."
Starmer, seeking to get on the front foot after some of his lawmakers said Downing Street's initial response over the weekend was not strong enough, has ordered an investigation into Mandelson's links with Epstein during Brown's government.
Brown, however, pre-empted him, saying that he had asked officials to look into the matter back in September but that he had been told they had unearthed no departmental records.
The former prime minister said on Monday that after the "shocking new information" came to light in the latest tranche of Epstein papers, he had asked for "a wider and more intensive inquiry to take place."
Starmer has also called for the former Prince Andrew to testify before a U.S. congressional committee, following new revelations about his links to Epstein.
Asked about the situation at a meeting in Dubai on Tuesday, Prince Edward, Mountbatten-Windsor's younger brother, said: "It's really important always to remember the victims", echoing previous statements from King Charles and Queen Camilla.
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(Additional reporting by Elizabeth Piper, writing by Paul Sandle; editing by Hugh Lawson, Mark Heinrich, Rod Nickel)