POLICE have warned drivers using the Membury service station, just outside Swindon, that tech-savvy thieves could be targeting their cars.

Officers have been investigating a series of thefts along the M4, including Membury, where no damage was done to the vehicles involved and the crafty criminals left no sign of a break-in.

It is feared that whoever is behind the crimes may be using radio-jamming transmitter devices to prevent the cars being locked before they strike.

Thames Valley Police said that, with the right knowledge, the jamming devices could be used to “interrupt” the signal that is sent from the owner’s key fob.

The result of this intervention would be that drivers might unknowingly walk away thinking that they had safely locked their car, where in reality they had not.

Thames Vally Police are investigating 14 recent thefts from lorries, vans and cars where “no obvious sign of a break-in” had been reported.

The force has advised drivers using the service stations to double check that their cars are locked before leaving them unattended.

The 14 incidents took place at Chieveley and Reading services, as well as Membury, over the last two weeks of November.

Remote keys, or fobs, have a unique signal which is transmitted via radio waves from the fob to the car.

Jammers overpower signals from the owner’s key and interfere with this communication.

The devices can be used over a large area, in theory allowing thieves to cover an entire car park.

Even more modern vehicles, including those with advanced anti-theft systems and advanced alarms, are susceptible to being targeted.

Investigating officer Sergeant Alan Hawkett, of Newbury Police Station, said: “I strongly recommend that any members of the public visiting motorway services stations anywhere in the country keep all valuable items in their possession when away from their vehicle.

“Offenders may be using technology to prevent your vehicle from locking therefore we would advise a manual check of the doors before leaving your vehicle.”

He also appealed for motorists who were using the services during the last weeks of November, particularly those with dashboard cameras, to get in touch.

“You may have captured an offence or offender on camera,” Sgt Hawkett said.

“I am extremely keen to review the footage.”