Peter Mandelson has used his appearance at the Leveson inquiry to attack former Met assistant commissioner John Yates, saying he considered taking him to court.
The former business secretary said he received a letter from Mr Yates accusing him of leaking information to the press at the very same time as it was "common knowledge" the policeman was briefing journalists himself.
"Writing me a letter like that showed such chutzpah," he told the inquiry.
"I also thought it was rather bullying. If I wasn't so busy being a European commissioner I might have thought it was a good idea to see him in court."
Lord Mandelson then expressed the widespread assumption in political and media circles that Mr Yates was leaking information to the press throughout the cash-for-peerages investigation.
"Mr Yates was aiming for high things in the Metropolitan police and since then people have contrasted his absolute determination - in a sense rightly and professionally - in the peerages scandal to the manner he set himself in relation to phone hacking.
"The [phone-hacking] inquiry was opened and closed down rather speedily by him."
The Met faced considerable criticism for the manner in which the cash-for-peerages investigation, which was conducted in a long and aggressive manner, failed to produce a single charge.
Lord Mandelson also confirmed Rebekah Brooks had asked him to "pull off" Murdoch critic Tom Watson from the media committee.
Describing the former News of the World journalist, Lord Mandelson said: "Persistence, charm, manipulative skills.
"Some might think that's a bit rich from me".