The police officer at the centre of the Plebgate row is seeking up to £200,000 in compensation from former Cabinet minister Andrew Mitchell.
Toby Rowland has filed court papers claiming that Mr Mitchell did use the term “f****** plebs” during their confrontation at Downing Street in 2012.
In the documents, revealed by the Mail on Sunday, Mr Rowland also implies that the ex-chief whip effectively apologised for using the words before later changing his story to save his career.
The claim has been lodged as part of the bitter libel battle between the MP, the PC and The Sun newspaper.
It is the first time Mr Rowland has spoken out since the incident. He claims that Mr Mitchell erupted after being blocked from cycling out of the pedestrian gate to leave the street, saying: “Best you learn your f****** place - you don't run this f****** government, you're f****** plebs.”
The politician has previously admitted to using “Anglo-Saxon” language, but said he did not swear at police, and flatly denied using the term “plebs”.
However, Mr Rowland alleges that Mr Mitchell telephoned him to apologise and that during their conversation there was the “clear implication he admitted to using the said words”.
The policeman is demanding up to £200,000 in “aggravated damages for slander” and has asked for an injunction to “restrain” Mr Mitchell, and those acting on his behalf, from repeating the claim that his version of the exchange was fabricated.
The libel claim lodged with the High Court is set out in a statement running to more than 10,000 words. It demands “damages including aggravated damages for libel, and if appropriate, slander”.
Responding to the news, Mr Mitchell reiterated his claim that he never used the term "f****** plebs".
He told the Mail on Sunday: “I have always made clear that the police account of what happened that night is untrue. Thanks to good investigative journalism much of the truth has already come out.
“There are ten police officers facing some form of misconduct inquiries for what they did and one has gone to jail, with three gross misconduct hearings taking place in London, starting tomorrow. My legal defence to these allegations will be filed shortly.”
Rowland’s lawyer Des Browne QC told the Mail on Sunday: "The claimant (Rowland) cannot say how much he expects to recover, save that he does not expect the amount in damages to exceed £200,000."
He added: "He has been very seriously injured in his personal and professional reputation and suffered great distress, humiliation and upset."
Following the Plebgate row, an independent report on the Police Federation of England and Wales found that major reform was needed in the institution.
And earlier this month chairman Steve Williams announced his departure from the Police Federation after leading major changes to the group following the report’s findings.
He said that he had been called a dictator and a traitor as he sought to reverse the organisation’s fortunes.
In February police officer Keith Wallis was jailed for twelve months for lying about witnessing the incident.