"White van man" is being encouraged to be more vigilant to combat a growing trend for commercial vehicle theft in West Yorkshire.

Opportunist thieves are walking into workplaces and taking keys or driving off in vans with the keys left in the ignition, according to police.

Two thirds of the 282 light commercial vehicles under three years old which were stolen between November 2001 and 2002 were taken with their keys.

DC Keith Preston, of West Yorkshire Police, said: "We're specifically appealing to the 'white van man' - or woman - to keep a closer eye on their keys.

"Don't leave keys lying around on workshop benches or in an office where they're easily visible to preying eyes.

"It's the simplest and quickest way to steal a vehicle and also the easiest to prevent."