Rogue telephone fraudsters are targeting older people with the offer of "energy saving devices" that could result in fire or electrocution.
The £99 plug-in device claims to save users 40 percent on energy bills, but actually poses a real risk to consumers.
The Trading Standards Institute (TSI) has been dealing with more than 200 complaints about the plug-in devices from companies claiming to be the victim's energy supplier, or working in partnership with them.
After testing a number of devices, the TSI found that not only do they not deliver any tangible energy savings, they also failed to satisfy electrical safety standards because the pins are too short and the internal connections faulty.
TSI chief executive, Ron Gainsford, said: "Consumers are warned not to use the product as they pose a risk of fire and electrocution, and a safety recall has been issued for the items traced so far.
Elderly customers targeted
"Unscrupulous criminals are using the rising energy prices as an opportunity to lure cash strapped consumers – elderly people seem to have been deliberately targeted. The number of complaints we are currently dealing with is bound to be only the tip of the iceberg."
Sue Jones from Westminster trading standards said: "The companies involved in these scams are not actually situated there. We believe the call centre they use is based abroad and the appliances appear to be distributed by a number of individuals in the UK."
Victims had told trading standards that the caller appears very credible - knowing the consumer's details including their energy supplier and even some or all of the digits from their debit or credit card, Jones said.
"Often consumers do not realise that they have been defrauded until they receive the dodgy looking device with instructions in broken English and the accompanying invoice which names an unknown supplier and often gives an American address," she said.
The plugs involved have the model number SD 001 and are manufactured by MacroPlus, B1208 City Square, Shenzhen, Guangdong, China.
So far, four different suppliers have been named – 1 Stop Marketing Solutions, ITC Development Corp, Power Saver, and Athico Ltd – but the TSI say fraudsters could be operating under other names too. And some of these names could be very similar to genuine companies: for example, Power Saver Ltd based in Tonbridge, Kent, is not involved in this fraud.
Consumers are advised that if they have responded to one of these calls to report the matter via Action Fraud's website or call 0300 123 2040, or call Consumer Direct on 0845 404 0506.
Trading standards also recommend they contact their bank to stop their debit or credit card, and if they have received a device they should not use it and dispose of it carefully.