Over 700 vehicles were stolen in a three-month period

It is the latest attempt by police to reduce car crime in the county.

Between October and December last, 720 vehicles were stolen after a spate of sneak-in burglaries.

Detective Inspector John Birkenshaw said that hi-tech car alarm systems are forcing criminals to search homes for car keys.

Security systems

He said: "It's an ever increasing problem.

"Manufacturers have played their part in crime prevention by making cars harder to steal with sophisticated immobilisers and security systems.

"It means the thieves need the keys to drive the car away."

And he explained criminals are going to extreme lengths to get hold of the keys.

He said: "We had a couple of incidents in the Bradford area where thieves were fishing keys through letterboxes.

"They will get up to any tricks to steal your car."