The head of the Metropolitan Police has told MPs he had an "open minded" approach to the "plebgate" investigation in the face of criticism that he hastily backed the police officers involved.

Met Commissioner Sir Bernard Hogan-Howe told the Home Affairs Select Committee he would "pursue the evidence" amid claims that former chief whip Andrew Mitchell was falsely accused of calling officers outside Downing Street "plebs".

Committee chairman Keith Vaz recounted Sir Bernard's assertion shortly after the allegations emerged that the Met boss would "stand by" his officers "100%".

Mr Vaz asked: "Are you still saying you stand by the events or do you now have an open mind?" To which Sir Bernard replied: "I do have an open mind. If any comment that I have made left anyone thinking I couldn't have an open mind, I'm sorry." He added: "I'm open minded. I will pursue the evidence."

Mr Mitchell was forced to quit his cabinet post over claims he called officers "plebs" during the altercation as the MP left Downing Street on his bike.

Mr Mitchell claimed he was the victim of a deliberate attempt to "toxify" the Tories and ruin his career after it was alleged an email from a civilian witness backing up the police account of events was in fact written by another officer.

A police officer and a relative have been arrested in the wake of the row while 30 detectives are now working on the investigation. Scotland Yard has decided to take statements from 800 police officers in the diplomatic protection group.

Sir Bernard added that part of the investigation was to identify the source of the leaked police log, which recounted the altercation with Mr Mitchell.

He told the committee that if the allegations against the police officers involved were true, "it would be a very serious matter". "I don't expect police officers to lie," he said.