Police have been accused of not recording smashed car windows as criminal damage.
Officers have allegedly been told to not always record car vandalism as a crime in a bid to massage crime figures.
It is understood that a memo from an unnamed police inspector in Norwich states that officers were too quick to assume a crime had been committed when people reported damage to their cars.
The memo reportedly reads: 'We appear to be making things difficult for ourselves by “criming” things that aren't actually crimes.
'Criminal damage is one of our highest recorded crimes and it is here where we appear to be doing this.
'One example is where a car window is found to be damaged, no entry to the vehicle, no witnesses and no idea how it happened.
'This has been recorded as criminal damage, even though there is no evidence to suggest it fits that definition.
'If there is no evidence of someone intending to destroy or being reckless then there is no crime.'
One officer, who asked not to be named, said: 'You can imagine the anger of a member of the public when a constable has to explain that the vandalism is not criminal damage.’
Norfolk Police denied trying to tamper with crime figures.