Online retailers have been criticised for selling gadgets that allow thieves to break into cars with electronic locks.

HackRF One is being sold on Amazon and eBay for £257 and can be used to intercept the radio signal from a key as a person unlocks a vehicle.

The signal is downloaded to a laptop and can be used by thieves to steal the car. The device is effective up to 30ft away.

Some manufacturers have introduced encryption to protect key signals, but the device features technology that can bypass it. In 2015 more than 6,000 cars and vans were stolen in London by criminals using car hacking devices.

Videos on how to use the gadgets are available on YouTube and HackRF One is sold for the “development of modern and next-generation radio technologies” by Great Scott Gadgets.

The packaging advises users that they are “responsible for using HackRF One legally” but the industry has called for government intervention.

Andrew Miller, chief technical officer at Thatcham Research, which tests vehicles, said: “Most of these technologies are designed for only one purpose, which is to break into a car. It tends to be organised crime which uses these devices and the problem is only going to get worse. The government needs to review the availability of these items.”

A spokesman for eBay said: “The device is widely available and is advertised as having a broad range of uses.We have not been advised of any restrictions on its sale.”

Amazon declined to comment.

Michael Ossmann, the founder of Great Scott Gadgets, said: “We encourage [carmakers] and automobile owners to use equipment such as HackRF One to test their own vehicles as permitted by law.”

YouTube said that it had “clear policies that outline what content is acceptable to post and we remove videos violating these policies”.

Jaguar Land Rover said: “Jaguar Land Rover is concerned but aware of the illegal use of equipment used to attack security systems on modern vehicles. We have a dedicated team working tirelessly with the aim of keeping customer vehicles secure from these criminal gangs who are continually attempting to devise new ways of hacking into vehicles.”