The Dutch police union NPB made an appeal to parliament for increased funding on Tuesday, saying criminals are going unpunished because of the shortage of detectives. In total, the police need 2,000 more detectives to make sure all cases can be followed up, the union says in a new report, which is in the hands of broadcaster NOS.

The report, based on interviews with 400 detectives, says the force is grappling with too many problems and nothing has been done to improve the detection service since the alarm was last sounded two years ago.

Detectives estimate just one in five cases – usually involving murder, armed robbery and violent crime – is picked up. Just one in three requests for observation teams or digital experts is honoured, leading to cases being abandoned or taking unnecessarily long to be completed, NOS quotes the report as saying.

This means other forms of crime, such as fraud, drugs and sex crimes don’t get the attention they should, the union says.

‘Over the past 25 years, I have seen small time dealers turn into major entrepreneurs with good contacts among politicians and into so-called respectable investors,’ one detective, named in the report as Bert, said.