Thieves are targeting cars in car parks around High Wycombe and stealing their catalytic converters, police are warning.

A catalytic converter is an exhaust emission control device that converts toxic gases and pollutants in exhaust gas into less-toxic pollutants - but gangs have been stripping them from vehicles so they can cash in on lucrative prices for rhodium, palladium and platinum in the devices.

The metals can be recycled for use in jewellery, dentistry and electronics.

Thames Valley Police said the thefts can take place in minutes - with the cars jacked up, the catalytic converters sawn off and then the thieves fleeing the scene.

Officers in High Wycombe say mainly Toyota Prius and Honda Jazz models are being targeted in multi-storey and open air car parks around the town.

Car owners are being urged to take measures to stop thieves being able to get hold of them.

They said: "Please help us look out for any suspicious activity and if you think you see a theft taking place then call us on 999.

"If you own a vehicle with a catalytic converter, when parking in a car park, try to park with the front of your car against a wall and avoid parking at the end of a row.

"This makes it harder for offenders to gain access.

"When parking at home, where possible park in a garage or in a location that restricts access underneath your vehicle.

"You may also want to consider installing CCTV to protect your vehicle."

Converters can also be etched with unique serial numbers so they can be traced and if the car parts are 'bolt-on', the bolts can be welded shut.