Police are warning car owners in Nelson and Clitheroe to be on their guard after a spate of catalytic converter thefts.
The devices, which convert vehicle exhaust emissions into less toxic gas, are targeted because they contain high value metals.
Honda and Toyota vehicles are some of the most common types to be targeted by thieves. Offenders have struck cars parked on residential streets, at business addresses and in public car parks including local supermarkets.
A spokesman for Lancashire Police said: "Catalytic converters are situated under the car, so persons illegally removing these would potentially be seen using a car jack to get to the underside of the vehicle, perhaps acting quickly and without proper protective tools and equipment to remove the converters.
"We have officers out in the community working with local businesses to identify potentially stolen goods attempting to be sold on, and we will be patrolling the area and will be available to speak with you about these issues if you need advice and reassurance.
"We are always looking at new ways to communicate these messages to those in the community, but If you have an elderly or disabled neighbour who might not see this message, please share this information with them to help keep each other safe.
"In the meantime, we would ask that you keep an eye out for suspicious activity in your neighbourhood, and if you see anything that doesn't sit right or anyone acting strangely to please contact us on 101. If a crime is currently taking place, call 999."