The senior Tory David Davis has called for a royal commission into police culture in the wake of the Plebgate row, claiming there is a "crisis of ethics" within the service.

Davis, a former shadow home secretary, said the Independent Police Complaints Commission should be beefed up to become a British "Untouchables", able to carry out investigations without obstruction. Davis – a close ally of former chief whip Andrew Mitchell, who resigned in the wake of a row with police at the gates of Downing Street – called for officers to be forced to wear cameras and microphones when on duty to record their actions as part of an effort to address a "decline in public trust".

Davis's intervention comes as three officers accused of trying to discredit Mitchell after a meeting in October last year are due to be questioned by MPs on Wednesday.

Police Federation representatives Inspector Ken MacKaill, Detective Sergeant Stuart Hinton and Sergeant Chris Jones will be questioned at a home affairs select committee inquiry into the row.

Mitchell, the MP for Sutton Coldfield, met the three officers from forces in the Midlands after he was accused of calling police guarding Downing Street "plebs" in a foul-mouthed rant as he was asked to cycle through a side gate on 19 September last year. Writing in the Times, Davis dismissed a call from Sir Hugh Orde, president of the Association of Chief Police Officers (Acpo), for a new ombudsman, arguing that the existing regulator should be given more powers.

"What we need is not a new regulator, but a tougher regulator. Earlier this year a parliamentary inquiry concluded that the Independent Police Complaints Commission 'has neither the powers nor the resources that it needs to get to the truth when the integrity of the police is in doubt'," Davis said.

"The government should respond by giving the IPCC the powers and resources to outrank and overrule every chief of police in the land – to become a British 'Untouchables'. Never again should a police force be able to delay or frustrate an IPCC investigation."

Davis said identifying problems after the event was not enough – the wider "crisis of ethics" needed to be addressed by a royal commission. He claimed the Mitchell case was the "latest in a long list of police investigations set up to seek the truth but conducted as clumsy cover-ups". "Britain needs root-and-branch reform of policing culture, a feat beyond the powers of even a powerful independent regulator," he said. "The government should appoint a royal commission to investigate the conduct of the police. The lessons about what behaviour is expected from a British police officer should be instilled from day one. "Of course, the commission should not limit its focus to new recruits. In recent days, as the truth about Andrew Mitchell's meeting with Police Federation officials has emerged, it has been senior officers who have responded with a series of implausible denials. The mindset of the whole officer class should not be off limits." Davis said technology such as cameras and microphones could help and their evidence could also offer police officers protection against false complaints.

"The police put millions of innocent people under surveillance in order to catch a tiny minority of wrongdoers. Perhaps now it is time to make officers wear a camera and microphone while on duty.

"When they tried this in California, use of force by police officers dropped by two-thirds in a year. This technology could also help to defend police officers who have vexatious claims made against them."