MISTAKES by police and prosecution lawyers are blamed today for the last-minute cancellation of one in every six trials in magistrates' courts in the region.

North Yorkshire's criminal justice service has one of the worst records in England for "cracked and ineffective trials" which fail to go ahead on the planned day - to the anger of victims and witnesses.

About 17 per cent of North Yorkshire trials in the year to March 2005 were dropped because the Crown Prosecution Service (CPS) or the police were not ready.

In contrast, only nine per cent were delayed in Cleveland and seven per cent in Durham, according to a National Audit Office (NAO) report published today.

It said errors by the police and prosecution wasted more than £55m every year across England and Wales, although no figure was provided for North Yorkshire.

The NAO criticised the CPS for:

l Switching lawyers presenting individual cases - a survey suggested the same prosecution lawyer was present throughout in only 15 per cent of cases.

* Lack of preparation before hearings - with lawyers struggling to prepare because they received the files less than 24 hours in advance.

* Failure to give priority to urgent cases - which meant necessary action was not taken in time for a hearing.

* Mislaying files - which were misfiled, or taken home by a lawyer.

The police, in turn, were blamed for leaving evidence out of files passed to the CPS - the cause of 35 per cent of delayed hearings.

Edward Leigh, the Tory chairman of the Commons' Public Accounts Committee (PAC) which works closely with the NAO, said: "The cost of this ineptitude goes beyond wasted cash."

Mr Leigh said prosecution lawyers performed a difficult job under serious pressure, but said CPS practices must be sharpened up and brought up to date.

The NAO - which surveyed 7,000 magistrates' court hearings over one week - pointed to an imbalance which meant the CPS had too many administrative staff and too few lawyers.

In all, 28 per cent or 784,000 hearings were delayed or ineffective in England and Wales each year, costing the taxpayer £173m a year.

The NAO made a number of recommendations, including making more time available for the prosecution to review and prepare cases and prioritising some cases.