Scotland Yard is under renewed pressure to allow an independent watchdog investigation of the "Plebgate" affair after Andrew Mitchell issued a formal complaint against it.
The senior Tory MP, who quit the Cabinet amid a storm over claims he called officers "plebs", accused the Metropolitan Police of a sustained campaign to "destroy" his career.
He has called on the Independent Police Complaints Commission (IPCC) to look into the apparent leaking of details of the findings of the probe into his claims that he was framed.
"We are deeply dismayed that the Metropolitan Police appear to have leaked part of their report prepared for the Crown Prosecution Service (CPS) to certain members of the press and spun it to the advantage of the police officers involved," Mr Mitchell wrote.
In a letter to IPCC deputy chairman Deborah Glass - which the watchdog confirmed it had received and would examine - he went on: "This was an enquiry into a dishonest and illicit attempt to blacken my name and destroy my career. It would appear that this police enquiry continues precisely that process."
A number of newspapers carried reports that documents submitted to the Crown Prosecution Service last week contained no evidence that officers had lied.
Keith Vaz, Labour chairman of the Commons home affairs committee, said the latest development reinforced fears that it was wrong for the force to look into the case. It provided a "good opportunity" for the IPCC to take full control, he said.
Mr Mitchell admits swearing at officers who refused to allow him to ride his bicycle through the main Downing Street gates, but strongly denies calling them "plebs". Papers related to the case were passed to prosecutors on Thursday, but the CPS said it was not "a full file of evidence" and that it expected more. "We now await the conclusion of the police investigation before considering charges," it said in what was seen as a further rebuke to the force.
The Metropolitan Police said its inquiries into the matter were continuing. It is trying to establish how the Sun and Daily Telegraph obtained information about September's altercation and whether it came from police. The Met is also looking at a police officer's claim to have witnessed the row and allegations by Mr Mitchell that police had lied in a log of the event.
Three officers from the Diplomatic Protection Group have so far been arrested as part of the investigation. All three remain suspended.