Norfolk's most senior detective last night had to defend the force's integrity after it was found to have “under-reported” the number of serious violent crimes.

Norfolk's most senior detective last night had to defend the force's integrity after it was found to have “under-reported” the number of serious violent crimes.

Det Chief Supt Julian Blazeby spoke in a bid to restore public confidence following the latest accusation that the force had misled the public over true crime levels. He insisted the misreporting of a “small number” of violent crimes had been unintentional and not altered the way victims were treated.

The error saw certain crimes downgraded because, though there was an intention to cause serious injury, no injury actually resulted. According to Home Office guidance these offences should have been grouped with the most serious violent crimes.

Norfolk, along with Suffolk and Cambridgeshire, was one of 18 of the 43 police forces in England and Wales involved. It means that rather than the fall in serious violent crimes originally claimed, there was actually a national increase of 22pc compared to the previous year.

Norfolk police's media director Anne Campbell said the revelation was unfortunate as it threatened to detract from yesterday's publication of positive figures showing a drop in overall crime of 9.4pc between July and September.

The news led to a major political row with shadow home secretary Chris Grayling claiming: “This undermines both confidence in crime stats and our ability to fight crime. If you don't measure a problem properly, you cannot combat it.”

Mr Blazeby admitted there were “some areas which could be misleading”. He added: “We can understand how some people would interpret that as under-reporting. But the integrity of our crime figures has been questioned and that is unfair.

“We have always recorded these crimes. It is not correct to describe it as 'under-reporting' because this change had no impact on our overall crime figures. It was simply a matter of what category these offences should fall into.

“This was due to a change in Home Office guidance which some police forces implemented earlier than others. We have now made the adjustment and are confident that any future changes will be implemented immediately.

“The most important issue here is that it did not affect our response to victims - it is force policy to visit every victim of crime. But I do acknowledge the importance of public confidence in our statistics.”

He added that “less than ten” incidents were involved. These were all incidents of grievous bodily harm which were classed as actual bodily harm.

According to the Association of Chief Police Officers, the confusion came down to the ambiguous nature of the guidelines used by officers to class crimes prior to prosecutions. There was no intention from any of the implicated forces to deliberately or knowingly downgrade violence.

A spokesman said: “There is no suggestion that forces have not been ethically recording violent crime.

“The Home Office picked out 18 forces as a way of drilling down into some of the areas where statistics had been particularly affected by the change to the counting rules to better understand the impact of those changes.

"That does not mean those forces were recording in a different way to others. All police forces record crime according to their best understanding of guidance provided.”

The latest Norfolk crime figures show violent crimes has reduced by 14.6pc - or 438 fewer offences. Theft was down by 9.1pc, criminal damage by 11.3pc and burglary by 2pc.

Mr Blazeby said: “The reality is that Norfolk is very safe. It is one of the safest counties in the country with one of the lowest crime rates per thousand population and we have pledged to further reduce crime.

“We work very hard to maintain this picture and the latest crime figures show that during the period July 1, 2008, to September 30, 2008, crime continued to fall by 9.4pc in total. This equates to 1,320 fewer crimes than the same period the previous year.”

In May last year police chiefs defended themselves after it emerged that a memo had been sent to some officers asking them to think again about whether some types of vandalism should be treated as crimes. The memo was an error of judgement by one officer which was open to misinterpretation and did not represent force-wide policy.

Then in October it emerged that 41pc of crimes reported in the county were “screened out” by civilian call handlers. Deputy chief constable Ian Learmonth insisted that all victims would be visited - even if the crime was less serious or judged to be unsolvable.