LONDON — Britain’s ambassador to the United States said he felt profound regret and embarrassment for his friendship with Jeffrey Epstein, after a birthday note he wrote for the disgraced financier in 2003 calling him “my best pal” was published by U.S. lawmakers.

Peter Mandelson told the Sun’s “Harry Cole Saves The West” show that he found the message — released by the U.S. House of Representatives Committee on Oversight and Reform as part of a tranche of documents on Epstein — “very embarrassing to see and to read.”

But he teed up the prospect of more damaging exchanges between the pair to come and admitted he “accepted assurances that he had given me about his indictment.”

“I just feel two things now,” Mandelson said. “One, I feel a tremendous sense, a profound sense of sympathy for those people, those women, who suffered as a result of his behavior and his illegal criminal activities.

“Secondly, I regret very, very deeply indeed carrying on that association with him for far longer than I should have done.”

Mandelson, a veteran of Tony Blair’s government who was a Labour MP at the time of the 2003 letter, said he regretted “very much” falling for Epstein’s “lies” and “accepted assurances that he had given me about his indictment … at face value.”

“I felt it like an albatross around my neck since his death,” he said.

Mandelson said he “never saw the wrongdoing” nor “any evidence of criminal activity” on the part of Epstein, who “never sought and nor did he offer” any introductions to women.

“Perhaps it’s because I am a gay man,” Mandelson said. “When I was associating with him those years ago, as I did with my then-partner and now husband Reinaldo, we never, ever saw any evidence or sign of this activity which has since come to light.”

He admitted: “I have no doubt at all that there’s a lot of traffic, correspondence, exchanges between us.”

Mandelson said: “We know those are going to surface, we know they’re going to come out, we know they’re going to be very embarrassing, and they know that I’m going profoundly to regret ever having met him and been introduced to him in the first place. But I can’t rewrite history.”

Mandelson said he had not discussed the topic with U.S. President Donald Trump — who is also facing a host of questions over his association with Epstein — or British Prime Minister Keir Starmer, whose government continues to back Mandelson for the key diplomatic post in spite of the row.