Mobile spy-cameras are being used as the latest weapon in the war on road-tax dodgers in Bradford, it was revealed today.

The new Stingray cameras are hidden in vans and can be parked up in lay-bys or on motorway bridges and trained on the number plates of moving vehicles travelling at more than 100mph.

A split-second check will reveal which cars are unlicensed and an electronic image will be stored of the guilty motorists. A letter will then be swiftly dispatched to the culprits warning them to pay a fine or face prosecution.

The hi-tech cameras will be used by officers from the Driver and Vehicle Licensing Agency officers in their latest campaign to snare some of the estimated 47,000 unlicensed vehicles on the road in West Yorkshire - 6,300 of which are in Bradford.

Wheel-clamping units will work in tandem with the camera crews along with West Yorkshire police during the crackdown. It is aimed at trapping motorists throughout the Yorkshire and Humber region who cost the agency £15.3 million in lost Vehicle Excise Duty revenue last year.

Thunderbird puppets Lady Penelope, her butler Parker and the FAB 1 car - stars of the 1960s children's show - will be used in a TV commercial to highlight the scheme.

According to the DVLA, 47,000 vehicles in West Yorkshire are unlicensed, the highest number in the whole of the Yorkshire and Humber region which has a total of 130,000.

Leeds has the most offenders, with an estimated 13,100 drivers who do not pay their road tax, while Bradford's figure is 6,300 and Wakefield has 3,100 motorists who flout the law.

But A DVLA spokesman said the figures alone do not tell the whole story. The spokesman said: "What you have to remember is that Leeds is a lot bigger than Bradford, and it is the same when comparing Bradford to Wakefield.

"The message we want to get across is that there will be no exceptions, no excuses and no escape - wherever you live."

The Stingray camera crews will start their patrols from April 22.

The DVLA has clamped more than 82,000 unlicensed vehicles in Great Britain, and more than half were crushed after they were left unclaimed.