Britain has sacked Peter Mandelson as its ambassador to the United States over his relationship with the late convicted sex offender Jeffrey Epstein, its foreign ministry said on Thursday.

Mandelson, a veteran Labour politician who was key to the party’s success under former leader Tony Blair, came under heavy scrutiny over his relationship with Epstein after a birthday book was released, including a letter purportedly from Mandelson describing Epstein as “my best pal”.

“In light of the additional information in emails written by Peter Mandelson, the prime minister has asked the foreign secretary to withdraw him as ambassador,” Britain’s foreign ministry said.

“The emails show that the depth and extent of Peter Mandelson’s relationship with Jeffrey Epstein is materially different from that known at the time of his appointment.”

The ministry said the revelation of Mandelson’s suggestion that Epstein’s first conviction was wrongful and should be challenged was “new information.”