Scotland Yard has said it will take years to root out rogue officers serving in the capital as “the size of a small police force” is suspended or on restricted duties.

Britain’s biggest force revealed that 201 officers were suspended and 860 were on restricted duties, equivalent to the size of Warwickshire or Wiltshire police forces. There are 34,000 police officers in the Metropolitan police.

An overhaul of culture and standards within the Met, prompted by the crimes of David Carrick and Wayne Couzens, has led to 100 dismissals for gross misconduct in the last 12 months, a 66% increase on historical averages, the force said.

Deputy assistant commissioner Stuart Cundy, who has been leading the reforms, said it would be years before the work was done. He said a “paradox” in the process meant the harder they worked, the more cases of misconduct and possible criminality would be uncovered.

Cundy said: “The harder we work, the more effort, the more energy we put into identifying those who shouldn’t be in policing, and doing everything we can in the regulations and the law as it stands, the more difficult cases, the more difficult stories will become public, and rightly so.

“And this isn’t something which we can resolve alone as the Met police, and isn’t something which we can resolve in one month, six months … this is going to take one, two or more years to root out those who are corrupting policing.”

The work to clean up the Met comes at a time when the policing watchdog in England and Wales has said “public trust in the police is hanging by a thread”.

Andy Cooke, the head of His Majesty’s Inspectorate of Constabulary and Fire and Rescue Services (HMICFRS), in his most recent annual assessment demanded sweeping new powers to compel police forces to tackle what he described as the worst crisis in law and order in living memory.

He said there was a limited opportunity to restore public trust in police before it was irreparably damaged.

Since the conviction of Carrick, a serving officer unmasked as one of the worst serial sex offenders in the UK, 1,600 cases have been identified where officers had faced allegations of domestic or sexual violence over the past 10 years but no action was taken.

There are about 450 investigations into the cases that were reviewed.

The Met also revealed updated figures about disciplinary processes, including:

  • 100 officers have been sacked for gross misconduct in the past year, up by 66% on the normal rate.

  • 201 officers are suspended, up from 69 in September last year.

  • 275 are awaiting a gross misconduct hearing, a significant proportion of which involved alleged violence against women and girls, compared with 136 last year.

  • The number of reports from the public and officers of alleged misconduct has doubled.

The force has also checked all officers against records on the police national computer, uncovering 11 cases that were subject to further assessment and five are now gross misconduct investigations.

Details of all Met employees, civilian staff and police, were also checked against intelligence records on the police national database. Fourteen are under further investigation for potential gross misconduct, with more due to be added.

The most serious of all the cases reviewed involved rape allegations, Cundy said.

A separate report is being published on Operation Leven, the name given to the overhaul of the parliamentary and diplomatic protection command (PADP).

The reform programme was prompted by both Carrick and Couzens, who was convicted of the kidnap, rape and murder of Sarah Everard while a serving officer, having been part of the PADP.

Officers in the unit are responsible for protecting the parliamentary estate, including the Palace of Westminster, as well as embassies across the capital. Most of the officers are armed.

The findings of Operation Leven were provided to Louise Casey, whose damning report on Met standards and culture was published in March.

Deputy assistant commissioner Laurence Taylor said the Operation Leven review found “unhealthy work cultures” with PADP arising from a “lack of diversity, poor and minimal loss of supervision, and a sense of disconnect from the Met” with low morale.

“It’s very clear that it needed to be better led, the officers need to be better supervised, they need to be better trained, and they need to be better equipped,” Taylor said.

Among changes being brought in, Taylor said the Met aimed to boost the number of women in the command to 20% and the number of black, Asian and minority ethnic officers to 20%.