Dozens of carbon monoxide alarms sold over Amazon and eBay have been withdrawn from sale after failing safety tests.
Four alarms available for sale on the retail websites failed to detect the presence of the gas, making them potentially lethal in the event of a carbon monoxide build-up in a home, an investigation by Which? found.
The consumer group urged anyone who purchased one of the devices – which all claimed to meet British safety standards – to replace them.
One of the alarms, the Topolek GEHS007AW CO, failed to detect the gas in more than 80 per cent of the tests conducted by the watchdog. It was bestseller on Amazon, where it retailed at £14.99.
Three other unbranded alarms, made in China and sold through Amazon and eBay for less than £10, also repeatedly failed to sound when there was carbon monoxide in the air.
Which? advised anyone who owns one of the alarms to replace it immediately and to contact the company they bought it from for a full refund.
Which? calls for government to take 'more active role' in product safety after investigation exposes dangerous devices.