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CCTV footage has been released showing thieves using a "relay" device, which receives a signal from the victim's key inside their home, to steal a car.

West Midlands Police believe it is the first time the high-tech crime has been caught on camera.

Relay boxes can receive signals through walls, doors and windows but not metal.

The theft took just one minute and the Mercedes car, stolen from the Elmdon area of Solihull on 24 September, has not been recovered.

In the footage, one of the men can be seen waving a box in front of the victim's house.

The device receives a signal from the key inside and transmits it to the second box next to the car.

The car's systems are then tricked into thinking the key is present and it unlocks, before the ignition can be started.

Mark Silvester, from West Midlands Police's crime reduction team, advised using a Thatcham-approved steering lock to cover the entire steering wheel.

The Society of Motor Manufacturers and Traders said an option was to put keys inside an RFID signal blocking bag, which stop electromagnetic signals.