Electrical Safety First found that the three heaters it bought through online advertisements (Keilini brand, HeatPal and InstaHeat) posed a serious risk of electric shock as the plugs did not meet UK safety standards.

The charity tested the heaters after seeing advertisements claiming they would help households save on their energy bills. You bought them through links within the ads.

Two of the heaters had plugs so poorly made that there was a risk that the plugs would break when plugged into an electrical outlet, putting the user at risk of electric shock.

The Keilini heater did not have any UK plug but was instead fitted with an EU mains plug and a very dangerous low quality UK travel adapter with no fuse creating a fire hazard.

All three heaters were missing the standard CE markings for safety.

The charity investigated after seeing advertisements claiming the devices would help households save on their energy bills.

Electrical Safety First chief executive Lesley Rudd said: “It is insensitive that these sellers are promoting dangerous products that they know financially distressed households are going to seek out during an energy crisis.

“Consumers are handing over their hard-earned money and, in exchange, receiving a product that puts their safety at risk.

“The safety claims found in advertisements for these heaters are very misleading. We urge shoppers to stick with reputable major stores or go directly to their online websites to ensure that the product they are purchasing is safe.”

The charity has reported its findings to the Government’s Office for Product Safety and Standards and the Advertising Standards Authority (ASA).

Last month, the ASA banned four ads for mini electric heaters for misleadingly suggesting they could provide heating cheaper than gas and save households money.

Advertisements for InstaHeat, Keilini, Heater Pro and Heater Pro X suggested that they were a cheaper alternative to gas central heating and could quickly heat up a room.