Police are delaying arresting rape suspects and cancelling appointments with victims because investigators are being sent to staff football matches and festivals, a watchdog has warned.

Inspector of Constabulary Michelle Skeer made a string of recommendations as she urged forces to make improvements after also finding several of the officers in rape investigation teams at forces visited by the watchdog were trainees who were not fully qualified.

The proportion of suspects being taken to court for rape is still among the lowest levels recorded, with a charge rate of 2.6%, according to the latest available government figures.

The inspection findings come after Home Office-funded Operation Soteria was launched in 2021 in a bid to overhaul and improve how police investigated sexual offences and rolled out across all forces in England and Wales last year.

While too early to judge the programme’s success, the watchdog looked at progress so far at nine forces who had adopted the measures since its launch and concluded “major changes are required for it to be successful on a national scale”.

The report from His Majesty’s Inspectorate of Constabulary and Fire and Rescue Services (HMICFRS), published on Thursday, said: “In half the forces we inspected, Rasso (rape and serious sexual offences) personnel are routinely diverted to supporting events such as football matches and festivals.

“Forces should recognise that this means Rasso investigators end up cancelling appointments with victims or delaying arrests. It only adds to their workload pressure.”

In nearly every force, “half of Rasso teams are personnel who aren’t fully qualified and are still training”, it added.

Making 14 recommendations for improvement to chief constables and bodies including the National Police Chiefs’ Council (NPCC) and the College of Policing, Ms Skeer said: “For too long, victims of rape and serious sexual offences have been failed by the criminal justice system. Many struggle to come forward, out of fear of not being believed or being unable to access support.

“It is crucial the police respond effectively to these devastating crimes. That’s why Operation Soteria sets out a new approach and model in response, grounded in decades of research examining policing practice.

“Out of nine forces inspected so far, early signs of positive progress are being seen.

“But improvements are required to ensure Operation Soteria is implemented effectively.

“We recognise that forces are trying to make things better while dealing with high demand and limited resources.

“However, even with all these challenges, Soteria presents a major opportunity for the criminal justice system. We must keep up the momentum towards change and give victims the service they deserve.”

In May, then home secretary James Cleverly vowed to put more sex offenders behind bars after thousands of police officers were specially trained in investigating rapes in the wake of claims the offence had effectively become decriminalised.

At the time, the College of Policing said 4,540 officers in England and Wales had completed specialist training on investigating rape and sexual offences.

The college – the body responsible for police training – said officers had been trained in each of the 43 forces across the two nations but did not disclose how many officers per force have received the training.

A Home Office spokesperson said: “This Government will make sure victims of rape or sexual abuse get the justice they deserve.

“While we welcome the progress being made, in far too many cases victims are being let down. That’s why it is so important that the police continue to make long-lasting improvements and put perpetrators behind bars.

“We will carefully consider the recommendations made in this report and work with the police to make the changes victims deserve.”

Chief Constable Sarah Crew, the senior officer responsible for the operation, welcomed the report adding: “I am pleased to see that this first HMICFRS report found Soteria to be a true ‘game-changer’ for policing.

“It is important to note that we were at an early stage of implementation at the time of the inspection and, while the signs are positive and strong, we still have much to do to transform.”

The College of Policing has been contacted for comment.