Ex-cabinet minister Andrew Mitchell has launched a stinging attack on Scotland Yard over its inquiry into the 'plebgate' row.
In a letter to the Independent Police Complaints Commission, he claims the force leaked contents of its own report.
His letter accuses the police of a "dishonest and illicit attempt to blacken my name and destroy my career".
The Metropolitan Police said inquiries into the matter were continuing.
Mr Mitchell has repeatedly denied claims, first reported in the Sun, that he swore and called police officers 'plebs' but he later resigned as chief whip.
He is suing the Sun over those claims.
A spokesman for the Sun newspaper said: "We stand by our story and will defend this claim vigorously."
Asked about Mr Mitchell's complaint to the IPCC, a Met Police spokesman said "our inquiries continue".
The spokesman added that the Met had "sent a report to the Crown Prosecution Service on Thursday as part of our investigation and a copy of this file was also sent to the Independent Police Complaints Commission, as they are supervising our investigation".
So far four people - including three police officers - have been arrested as part of the investigation into the incident, which happened in September last year.
Initial reports had said that the former Conservative cabinet minister lost his temper and allegedly swore at police when they refused to open the gates for him as he cycled out.
Mr Mitchell admitted there was an exchange and resigned from the cabinet - but denied directly swearing at any officers and denied using the word "pleb".
CCTV footage of the incident later cast doubt on the police reports.
Those arrested in relation to the incident include:
A 52-year-old from the Diplomatic Protection Group who was held on 15 December on suspicion of misconduct in public office and bailed until April
Two 46-year-olds from the same command were held on 31 January and 1 February for allegedly passing information to the media and were bailed until May
A 23-year-old man who does not work for the police was also arrested and bailed until May
All three police officers remain suspended.