Drivers are being warned to be vigilant following an increase in thefts of catalytic converters from vehicles.

Thieves have been targeting cars in Hertfordshire with a significant increase in Hertsmere and Watford.

Catalytic converters, which are fitted to the exhaust system, are targeted by thieves because of the precious metals they contain.

Inspector Andrew Palfreyman, from Hertfordshire Constabulary’s Crime Reduction Unit said: “Reports indicate that offenders are committing the thefts during the daytime, showing little regard for onlookers.

"We urge the public to remain vigilant and report incidents of catalytic converter theft, particularly where you see people acting suspiciously, jacking up or working under cars in public car parks or on public roads.”

Toyota Prius vehicles appear to have been a particular target, with more than half of recorded catalytic converter thefts in the county involving this model.

In order to minimise the chance of becoming a victim of catalytic converter theft police have said:

• Lock your car in a garage when parked at night.

• When using a garage is not possible, park close to fences, walls or a kerb with the exhaust being closest to the fence, wall or kerb to make theft difficult.

• Consider fitting CCTV to your home or driveway, to help deter thieves.

• Use PIR or LED security lighting to make your vehicle more visible and also as a deterrent.

• If your catalytic converter is bolted on, consider having the bolts welded to make removal difficult.

• Fit protective coverings on catalytic converters, such as the Toyota manufactured CATLOC device, (these are made for Toyota Prius made between 2004 and 2009) as these can make it much more difficult for thieves.

• Have your catalytic converter etched or forensically marked, and put stickers in the windscreen to say this has been done.

• Look for car parks with a Secured Car Park sign which have recognised levels of security.

• Noisy gravel on your drive can help deter a would-be thief, as they don't want to alert you to their approach.