British police have released a shocking video of how a Mercedes with keyless entry can be stolen in just 60 seconds.

The car, which can be unlocked and started so long as the key fob is nearby — such as in the driver's pocket — was stolen when thieves used a so-called 'relay box' to boost the key fob's signal from inside the owner's house, then passed that signal to the car.

West Midlands Police believe this is the first ever recording of a 'relay crime', as two men are seen approaching the car and house by a security camera.

Assuming the driver had left their key fob near the front door, one thief stood by the door with the relay box. This picks up the weak signal of the key, then boosts it and transmits the signal across a longer distance. The car picks this up and, thinking the key is much closer than it really is, allows the thieves to open the door, start the engine and drive off.

The theft took place at around 9pm on September 24 in Solihull, England.

Police have suggested owners of cars with keyless entry invest in a steering wheel lock and tracking system to help prevent similar crimes.

Some vehicles with keyless systems, including those sold by Mercedes, have a feature where a double-press of the key fob disables the keyless system, stopping the key from transmitting the signal captured by the relay box. The car is then unlocked with a press of the fob, which re-activates the keyless system.

An alternative would be to keep your key fob away from doors and windows at home, or place it inside a metal box when not in use.

Sergeant Tim Evans of Solihull Police said: "It's important the public are reassured that we are taking proactive steps to tackle this type of crime...We hope that knowledge of this type of crime will enable members of the public to take simple steps to secure their vehicle and assist us."