Police officers in Lincolnshire have been accused of failing victims of violent crime, rape and domestic abuse after a watchdog warned that almost one in five crimes reported to the force goes unrecorded.

According to a report released by Her Majesty’s Inspectorate of Constabulary (HMIC) on Tuesday, the force failed to record 18.8% of crimes reported between June and November 2017 – the equivalent of more than 9,400 crimes per year.

Branding Lincolnshire’s crime data “inadequate” against Home Office rules, HMIC inspectors said the probe had unearthed “unacceptable failings”, with officers lacking both knowledge and supervision regarding their crime-recording duties.

The watchdog said officers recorded less than three quarters (72.9%) of violent crimes reported to them during the six-month period, including serious offences such as GBH.

The inspectorate also found that 24 out of 123 audited rape reports were inaccurately recorded, with 11 of the missed incidents involving two victims of modern slavery, who had been coerced into prostitution.

While the force’s recording rate for sexual offences was considered “good” overall, it failed to record crimes against both adults and children.

Zoe Billingham, of HMIC, said while safeguarding measures were in place for many victims of unrecorded crimes, “there was little evidence of investigations being undertaken where the crime had not made it on the books”.

“The importance of correctly recording crime cannot be overlooked, or simply passed off as a bureaucratic measure,” she added. “If a force does not correctly record crime it cannot properly understand the demand on its services, nor provide support to those who need it most.” 

Billingham’s comments were echoed by Diana Fawcett, chief officer at charity Victim Support, who said failures by police to accurately record violent and sexual crimes puts “extremely vulnerable people at further risk” by preventing them from accessing help, support and justice.

She added: “We know there are already barriers to reporting to the police – especially of rape and domestic abuse – and news like this has the potential to further undermine public trust in the criminal justice system and deter people from reporting in the future.”

In a statement, Lincolnshire Police’s deputy chief constable Craig Naylor said the force was “deeply disappointed” by the report.

“We have made mistakes and we will not shirk from accepting and correcting them,” he said, adding that new measures for recording had been put in place since the inspection.

“Our focus and commitment is to ensure victims are at the centre of all that we do and I am confident that, despite issues in how we have recorded some crimes, that service has not slipped from the high standards we set ourselves.” 

Naylor added: “There are no ‘missed’ victims or offenders – what we have missed is the correct procedure for recording them.” 

The report comes as part of a rolling inspection by HMIC of every police force in England and Wales.

Data also released on Tuesday ranked the Metropolitan Police Service’s crime-recording rate as “good”, with the force recording almost 89.5% of reported offences. 

However, the watchdog estimated that Scotland Yard still fails to record more than 94,500 crimes a year, “potentially depriving some victims of valuable support services”. In 2017 alone, the force recorded more than 800,000 crimes. 

Meanwhile, Humberside Police force was told it “requires improvement” after recording 85.7% of crimes. A spokesperson said the service was “determined to keep on improving”.

The Metropolitan Police has yet to respond to HuffPost UK’s requests for comment.