An independent report has found evidence of police putting disproportionate effort into investigating the credibility of rape complainants and “explicit victim blaming”.

Findings from Operation Soteria, a programme aimed at transforming the way the police and CPS respond to rape cases, found that some officers “displayed a culture of disbelieving victims”.

Other serving officers do not think addressing rape and other sexual offences should be a priority for policing, while some believed most rape reports are instances of “regretful sex”.

It comes as the Government claimed that “significant progress” is being made in how the criminal justice system responds to cases of rape, 18 months on from the summer 2021 rape review.

Four forces were involved in the first year of Operation Soteria, which involved analysis of thousands of reported rapes and other sexual offences, investigation records and interviews with officers.

The report, published by the Home Office, found “disproportionate investigation effort was being put into testing the credibility of a victim’s account” in each force, with a need to “rebalance investigations to include a thorough investigation of suspects’ offending behaviours”.

Processes and procedure “often trumped” empathetic engagement with victims, while there was “great variability” in officers’ attitudes, beliefs, and behaviour concerning rape and sexual offences.

The report said: “At worst, officers demonstrated explicit victim blaming and lack of belief in the victim, which impacted on the subsequent investigation.

“For example, victim credibility was often focused on and used to either close or not investigate cases within some forces.”

It added: “Challenging internal cultures which undermine fair and equitable rape investigations is necessary as a matter of urgency.”

The report found that police investigators lack sufficient specialist knowledge about sexual offending, which impacts on victim engagement and the quality and outcome of investigations.

Inexperience and “worrying” levels of burnout were also identified.

Home Secretary Suella Braverman said the report shows there are “big obstacles to overcome”, adding: “But there are also early signs of improvement and I’m determined to build on these to deliver a sustainable shift in the way rape is investigated.”

Chief Constable Sarah Crew, National Police Chiefs’ Council lead for adult sexual offences said many findings are “challenging, and some are concerning”, adding that the programme had been met with “a genuine willingness and openness to change”.

She said: “Officers must target rapists by focusing on suspects, not the credibility of victims, and using their legal and policing powers to disrupt offenders and further harm.”

Andrea Simon, director of the End Violence Against Women Coalition (EVAW), said: “This report serves to further highlight what women’s organisations have long known: that cultural issues of misogyny, sexism and racism in policing impact whether or not victims have access to justice, as well as how they are treated during the process, being disbelieved, blamed and stereotyped.

“This is compounded by serious workforce issues including a lack of specialism and experience when it comes to investigating rape and other serious sexual offences, with officers shockingly undermining the seriousness of this violence.”

The Metropolitan Police, which is one of the initial forces involved in the programme, said it is “committed to transforming its response to rape”.

Commander Kevin Southworth said: “We are working hard to boost detection rates, cut the backlog of cases and reduce the amount of time victim-survivors spend waiting for justice.”

A separate progress report published by the Government said it is “on track” to meet its target to more than double the number of adult rape cases reaching court by the end of this parliament.

It cited increases in police referrals, charges, convictions and cases reaching court, while the average number of days between a police referral and a suspect being charged has fallen.

However, the progress report acknowledges that the time it takes for a case to reach court has “worsened”, while the number of outstanding cases has risen, with the Criminal Bar Association strike cited as a factor.

A joint foreword, by Justice Secretary Dominic Raab and victims and sentencing minister Ed Argar, reads: “A year and a half on, there is cause for cautious optimism.

“We are making steady, incremental progress.”

The report cites latest criminal justice data showing that 901 cases were referred by the police to the Crown Prosecution Service (CPS) in the second quarter of 2022, up 95% from the 2019 quarterly average.

The number of cases charged by the CPS in the second quarter of 2022 has risen by 65% to 402, compared to the quarterly average in 2019.

The number of adult rape cases reaching crown courts has also risen, with 440 receipts, up 91% from the pre-pandemic quarterly average.

And the number of adult rape convictions was 41% higher than pre-pandemic levels in the year to June 2022 (532 up from 377).

However, since April the number of outstanding cases in the crown courts has been rising, after falling between June 2021 and March 2022, reaching 62,500 cases at the end of September.

And the report said that timeliness at the court stage has worsened, acknowledging that waits for trials can cause “significant distress”.

Mr Raab and Mr Argar said they are “restless to go further and faster for rape victims”, adding: “Huge challenges remain.”

Kirsty Brimelow KC, chairwoman of the Criminal Bar Association, said: “It is encouraging that more cases are reaching court.

“However, this is a basic and complainants are waiting years for trials.”

She added that there are not enough barristers to prosecute in trials and quadrupling funding for support is “senseless” without investing to ensure there are enough barristers.