Metal thieves are now targeting car owners and stealing catalytic converters for the platinum inside.

There have already been at least six thefts in Oxfordshire in the past three months, but others may have gone unreported.

A catalytic converter can net the thief up to £120 because it contains much sought-after platinum and other precious metals.

Det Insp Andy Nicklin said: "They are part of the wider issue of metal thefts and so far we have had a small number of catalytic converters being stolen in Oxfordshire."

A catalytic converter was stolen from a Peugeot van in Park Road, Faringdon, at about 7.30pm on April 18.

On April 29, a catalytic converter was stolen from a Ford Focus parked in Tyrell Close, Stanford in the Vale, followed by a theft from a Honda Civic in Perry's Road, Stanford in the Vale, on April 30.

Pc Lewis Boyce is appealing for information about a white Transit van seen in Park Road and reports of a tall, slim, white man wearing a three-quarter-length jacket, with the hood up, who was seen carrying a vehicle jack in Tyrell Close.

The converters have up to 3g of platinum as well as other precious metals including palladium and rhodium.

The cost of platinum has trebled in the past 18 months and now stands at £1,000 an ounce.

Call police on 08458 505505 or speak anonymously to Crimestoppers on 0800 555111.