Half of the drivers who went past a police van equipped with the latest technology were identified as potential criminals during an operation in Bradford.

Within half-an-hour, West Yorkshire police force's Automatic Number Plate Recognition (ANPR) system had identified 200 of the 400 vehicles as suspicious.

The system reads the number plate of each vehicle and alerts officers to any which are stolen or connected to known offenders.

It also can pick out road-tax dodgers - although some vehicles which come up as "hits" may have been taxed recently and this would not yet been registered on the system.

The swoop in Harrogate Road yesterday - part of the Operation Target crackdown - involved a police van with a specialist computer and two spy cameras which store an electronic image of the vehicle and carry out a split-second database search.

The controlling officers then notify waiting officers in police cars or on motorcycles who stopped the suspicious vehicle for checks.

Officers identified a number of cars without tax discs, some which did not have a registered user and some which may have been involved in past criminal activity.

Officers also looked after a man who had collapsed a few hundred yards from the police van until an ambulance arrived.

The van later moved to Manningham to target suspicious vehicles there.

Earlier in the week, the hi-tech equipment identified an untaxed car which turned out to contain drugs.

A search of the driver's home later revealed ten kilos of cannabis resin.

Sergeant Rudy Tanghe, who is in charge of the ANPR system, said: "This technology is the way forward in the fight against crime. The majority of criminals now use vehicles to commit crime and this is a weapon in our armoury to stop them."

Other issues tackled by police during the four-day crackdown have included drugs, street crime and anti-social behaviour.

The operation has included emblazoning the Target logo across Lister Mill in Manningham. A policing exhibition and consultation event was due to take place at Morrison's supermarket at Enterprise Five in Idle today, from 11am to 3pm.

Since Target was started in April 2001, almost 4,000 people have been arrested.