A police file passed to prosecutors on Thursday on the so-called "plebgate" affair contains no evidence that officers lied about an altercation with the former chief whip Andrew Mitchell in Downing Street, the Guardian understands.

The Crown Prosecution Service will examine the file to decide if any officers should be charged. However, on Thursday night, the CPS indicated it was unhappy with the file it had received from the Metropolitan police and was awaiting more evidence. The papers were submitted by detectives investigating the incident from September, which led to Mitchell's resignation.

The file contains evidence on the alleged leaking to the media of the incident, in which Downing Street officers said Mitchell swore at them and called them plebs. But it is understood prosecutors have not been passed any evidence that Metropolitan police officers were involved in a conspiracy to frame Mitchell, as the MP has alleged.

Mitchell's allies are likely to be dismayed by the findings of the police investigation into the actions of its own officers.

The sources said they would wait to see what the final reports from the CPS said about the case, but pointed out it has already been admitted that a police officer had masqueraded as a member of the public, and claimed to have been an eyewitness to an event at which he had not been present.

The Metropolitan police refused calls by Keith Vaz, chair of the home affairs select committee, for them to leave the investigation to the police watchdog, the Independent Police Complaints Commission. Vaz said the plebgate affair raised "fundamental questions about police honesty and integrity" and should be investigated independently.

Instead the IPCC was brought in to supervise the Met inquiry, led by assistant commissioner Pat Gallan. The Met commissioner Sir Bernard Hogan-Howe also called in another force, Greater Manchester, to provide an external review.

The controversy arose after Mitchell tried to ride his bicycle through the gates in Downing Street but was asked to dismount by the two officers on duty and walk through. They claimed he swore at them, called them plebs and warned them that was not the last they would hear of it – a story subsequently leaked to the press.The Met said on Thursday its investigation was continuing but a file of evidence had been passed to the CPS for decisions on charging.

Three Met diplomatic protection officers were arrested during the investigation into who leaked details of the altercation and whether – as Mitchell claimed – there was a conspiracy to frame him. Another four officers were warned they face disciplinary action over their behaviour.

Three Police Federation representatives from the Midlands who held a meeting with Mitchell and then called for him to consider his position, are facing disciplinary investigations by their forces over what they said to the media following the plebgate incident.

A Met police officer was also arrested as part of the investigation over an email he sent to the deputy chief whip in which he claimed to be a member of the public who witnessed the affair, even though he had not been present. Prosecutors will now decide whether to charge the 52-year-old diplomatic protection officer with misconduct. A relative of the officer was also arrested as part of the investigation.

A spokesman for the CPS said: "We have received initial papers but we have not received a full file of evidence and we now await the conclusion of the police investigation before considering charges."

The CPS will also consider charges against two other diplomatic protection officers – including a 46-year-old who was present at the Mitchell altercation – over allegedly leaking details of the incident to the Sun and the Daily Telegraph. The arrested officers have been suspended.

A spokesman for the CPS said: "We have received initial papers but we have not received a full file of evidence and we now await the conclusion of the police investigation before considering charges."

The investigation was launched after Mitchell obtained CCTV footage of the incident which appeared to cast doubt on the officers' claim that a number of passers by had witnessed the event and looked visibly shocked. He claimed that he had been set up by the police officers who had lied over what happened during the incident.

Friends of Mitchell said the former cabinet minister had this week served a writ against the Sun for "its campaign of vilification against Mitchell". A spokesman for the newspaper said: "We stand by our story and will defend this claim vigorously."

Mitchell admitted swearing in the presence of the officers but denied he had used the word pleb. After the initial article in the Sun, the log of the event which contained the word pleb was leaked to the Daily Telegraph.

Mitchell has never made a formal complaint to the police but he was interviewed as part of the inquiry.

Gallan's investigation examined who leaked details of the incident to the media, the circumstances around the claim that an officer had witnessed the incident, any evidence of a conspiracy between officers, and Mitchell's claims that police lied in their log of the incident.

Diplomatic protection officers are understood to have made clear to investigators that they face abuse on a regular basis in and around Westminster.