Former cabinet minister Andrew Mitchell has waged war on the Metropolitan police, accusing it of trying to destroy his career.
The former Chief Whip, who quit the post after the 'plebgate' affair, has accused the force of leaking an inquiry into the episode to reflect well on the officers involved.
In a formal complaint to the Independent Police Complaints Commission (IPCC), Mitchell said he was "deeply dismayed" that the Met appeared to be trying to "spin" the investigation.
It comes after press reports of the police file passed to the Crown Prosecution Service said there was no evidence that officers lied about his behaviour.
The senior Tory MP, who is also suing The Sun over its coverage of the affair, strongly denies calling officers "plebs" during an altercation over their refusal to allow him to ride his bike through the Downing Street gates last year.
He says he is the victim of a conspiracy by officers to "toxify" the Tories and blacken his name.
In a letter to IPCC deputy chairman Deborah Glass, he wrote: "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.
"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."
Keith Vaz, Labour chairman of the Commons home affairs committee, said the latest development showed it was wrong for Scotland Yard to lead the inquiry into its own officers and called for the whole investigation to be taken over by the IPCC.
Scotland Yard is trying to find out how the Sun and Daily Telegraph obtained information about the "Plebgate" row and if it came from police.
It is also looking at a police officer's claim to have witnessed the altercation 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.
Some 30 detectives have taken statements from all 800 officers in the DPG, which is tasked with protecting government officials.
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 is expected more.
"We now await the conclusion of the police investigation before considering charges," it said in what was seen as a rebuke to the force.
A number of newspapers subsequently reported sources as saying the file did not contain any evidence to back Mitchell's claim of a conspiracy by officers.
Vaz said the committee had argued from the start that Met Police Commissioner Sir Bernard Hogan Howe was wrong to allow Scotland Yard to conduct the investigation.
Britain's most senior police officer promised a "ruthless" investigation into the alleged conspiracy "no matter where the truth takes us".
It is being supervised by the IPCC and the commissioner invited the Greater Manchester force to provide an external review.
"I am very surprised that the police report has been leaked to selected journalists," Vaz said - adding that Mitchell would "rightly feel he has been badly treated by the current situation".
Calling for the Met to pull out of the investigation, he said: "This is a good opportunity for the IPCC to take over this investigation and use the information that has been gathered so far as background".
The Metropolitan Police said its inquiries into the matter were continuing.
Speaking on Sunday morning, Tory party chairman Grant Shapps said that if what Mitchell was alleging was proved, it would be "an incredibly serious matter, and something that should not be happening in a democratic country."