'Plebgate' police officer investigated over witness claims Met officer being investigated over whether his claim to have witnessed the clash between Mitchell and police was wrong or valid. A police officer arrested in connection with the "Plebgate saga" that saw the Tory chief whip, Andrew Mitchell resign, is being investigated for allegedly claiming to have been a witness to the row in Downing Street, it emerged. The officer from the Metropolitan police is being investigated over whether his claim to have witnessed the clash between Mitchell and police in September was wrong or valid, the Independent Police Complaints Commission said. The officer is also being investigated over whether an account of the incident, he is alleged to have given an MP, was accurate, the IPCC added. In an earlier statement the Met had said the officer had been arrested on Saturday over the leaking of information to the media about the clash which ended in Mitchell's resignation. The IPCC statement reveals he faces more allegations than first thought. The officer referred to by the IPCC is the same one the Met announced they had arrested over the weekend in connection with leaking of police material to the media concerning the incident with Mitchell. Mitchell, then the Tory chief whip, ended up resigning after he was alleged to have insulted police officers guarding Downing Street, by using the term "plebs." The IPCC said it would supervise an investigation to be conducted by the Met, into whether the alleged account of the incident made by the officer was accurate. An IPCC spokesperson said the police watchdog was not involved in any inquiry into the alleged leaking of police information to the media, though this strand was linked. The arrested officer was not on duty at the time of Mitchell's row with police, the Met has said. He is from the diplomatic protection group, SO6. In a statement the IPCC explained part of the investigation, which it is supervising: "The circumstances surround a serving police officer's claim to have independently witnessed a widely reported incident outside Downing Street in central London on 19 September 2012. The investigation is considering the validity of the officer's claim, which is understood to have been made to a member of parliament in a private capacity. The investigation is linked to inquiries by the MPS into how internal MPS information was obtained by national newspapers following the incident. Mitchell has said he "did not use the words attributed to me" and denied using the word pleb, although he has admitted to saying: "I thought you guys were supposed to fucking help us." On Monday Mitchell told ITV News: "I'd just like to reiterate once again that it's the contents of the alleged police log which are false ... they are false and I want to make that very clear." The Police Federation has expressed "great regret" after Scotland Yard arrested the officer from the diplomatic protection group, SO6, over the alleged leaking of information to the press about an incident at Downing Street in which Andrew Mitchell, the then chief whip, is said to have called officers "plebs." The row in September developed after police at Downing Street refused to open the main gates to allow Mitchell to take his bicycle through, instead forcing him to use the side gate. Weeks before Mitchell's resignation the Met launched an investigation into how the Sun obtained an internal report suggesting Mitchell did call the officers plebs.