Police cameras in one force area read and stored more than 233 million vehicle number plates last year - more than a fivefold increase on the previous year.

Out of the 233,852,149 images taken in 2008, more than 6,000,000 matched so-called "vehicles of interest" - ranging from those with no insurance to ones linked to known criminals.

The figures, released under the Freedom of Information Act, represent a steep rise on the previous year, when more than 44,500,000 images were taken on the roads of Sussex in 2007.

Sussex Police said all the pictures recorded are automatically encrypted, numbered and then stored on secure and encrypted computer databases.

But Charles Hendry, the Conservative MP for Wealden in East Sussex, said a balance must be struck between what is necessary for the police to gain information on potential criminals and the rights of ordinary citizens.

He said: "I know that the police are using this technology to help them track potential criminals but I find these figures staggering for a county the size of Sussex.

"I believe the populations of both East and West Sussex is somewhere in the region of two million, which means every motorist has been caught about 100 times in the past year.

"It is a widespread method used much more than any of us realised.

"My concern is that there needs to be a balance between what is necessary for the police and the rights of the individual to go about their every-day business without being snooped upon."

Digital images are captured through the automatic number plate recognition (ANPR) systems, located either in a mobile unit or at a fixed site.

The system is able to cross-reference the data against a variety of databases including the Police National Computer (PNC), DVLA and highlights vehicles of interest to police forces.

Acting Chief Inspector Steve Grace, of Sussex Police's road policing unit, said: "ANPR is becoming a very valuable tool for us in fighting crime and identifying criminals on the roads.

"The increase in the number of hits for Sussex through the ANPR system in 2007/08 is due to the fact that we have increased the numbers of both static and vehicle-borne systems."

Sussex Police have said that using ANPR has helped make some notable arrests, including that of a suspect for kidnapping in London and of an active burglar.

Figures published in the Daily Telegraph showed that the largest number of records were created by the Metropolitan Police with 342.8 million, followed by West Midlands Police with 267.6 million.

Paul Watters, the AA's head of public affairs, said: "ANPR is helping to reduce the scourge of millions of illegal drivers that cause carnage on UK roads, cost honest drivers extra money on their insurance, dodge the taxes that most other people pay and escape prosecution for motoring offences.

"The system gives the police the power to question drivers with vehicles instead of trying to trace the owners of parked cars. However, it is not a substitute for traditional road policing.

"The AA understands that many drivers are facing severe financial difficulties in the recession and DVLA data indicates that the number of drivers paying road tax is down, although much of that is due to lower new car registrations.

"However, there are many cash-strapped drivers who are sticking to the law and ANPR, along with close scrutiny on DVLA ownership databases, makes tax-dodging a dangerous gamble.

"The only downside with ANPR may be an increase in number plate thefts to clone cars, as seen with the London Congestion Charge."