Wiltshire Police are urging people to be vigilant following a series of thefts of catalytic converters.
Vehicles across the county have been targeted by thieves in recent weeks. In most cases, the perpetrators are removing catalytic converters from cars during the night.
A catalytic converter controls and converts exhaust emissions from a vehicle into less toxic substances but are valuable to thieves because of the precious metals used to make them.
Makes of vehicles that have been targeted so far include Citroens, Peugeots, Mitsubishis and Mercedes.
Sgt James Williams said: "We are invariably seeing a number of incidents occur across any given evening.
"The person or people that are committing these crimes are targeting cars in residential areas in the middle of the night. It isn't until the following morning that the owners of the cars realise what has happened.
"We've seen incidents occur in Melksham, Trowbridge and Devizes but I can reassure the local communities that we are currently carrying out a full investigation into the recent thefts."
Wiltshire Police would like to remind the public of some simple tips to keep their vehicles safe and secure from criminals targeting catalytic converters:
• Be vigilant - if you spot people working under vehicles or acting suspiciously in your local area, contact 101 immediately
• Store your car in a secure area - if you have a garage or area that you can use to securely park your car at night, utilise it
• If you can't park your car in a garage, consider leaving it in a well-lit area as close to your property as possible
• Taller vehicles such as 4x4s and vans may be more vulnerable as their catalytic converters are more accessible
• Fit a catalytic converter alarm system or security device.
If you suspect your catalytic converter has been stolen or have any information about the recent incidents, contact Wiltshire Police via 101 or Crimestoppers on 0800 555 111 where details can be left anonymously if preferred.