A smart plug for sale on Amazon poses a fire risk and people should immediately stop using it, an investigation by consumer watchdog Which? suggests.
Amazon said it had removed the Hictkon smart plug with dual USB ports from sale, pending investigation.
Its live connection was too close to an energy-monitoring chip, Which? found.
And this could cause an electrical discharge between two electrodes, posing a fire risk particularly in homes with older wiring.
'Burning hoverboards' The investigators also said the product's CE mark, normally associated with having passed rigorous European safety standards, was misleading.
Some Chinese companies use a similar CE mark to designate "China export".
Others simply fake the safety mark because there is no central database to check whether it has been verified and it can be self-declared by companies.
"Companies get away with it until they don't," said Clever Compliance chief executive Max Stralin.
"The same issue arose with the burning hoverboards back in 2015.
" 'Dangerous products' Amazon said customers concerned about purchases should contact its customer-service team.
"We monitor the products sold in our stores for product-safety concerns," it said.
"When appropriate, we remove a product from the store, reach out to sellers, manufacturers and government agencies for additional information or take other actions.
" But Which? Computing editor Kate Bevan said: "Too often we've seen dangerous products being sold on online marketplaces from unknown brands - in many cases originating from China's electronics capital, Shenzhen - that appear to have little accountability and are virtually impossible to contact.
"This raises big concerns around safety checks and monitoring carried out by online marketplaces like Amazon.
"Currently, consumers face a lottery regarding the safety of the products they buy from online marketplaces and whether they meet required safety standards in the UK.
"That's why it's vitally important that the government gives online marketplaces more legal responsibility for preventing unsafe products from being sold on their sites.
" Muscle massagers She called for government legislation and an "enforcement body with teeth" to crack down on rogue devices.
Hictkon products, which include muscle massagers, ultraviolet lamps, touchscreen monitors and Hallow-e'en masks, are available only on Amazon, according to Which? Many of the top 10,000 UK sellers on online marketplaces were also based in China, it said: 36% on Amazon Marketplace 30% on eBay 95% on Wish But Amazon allows some sellers to ship products to its UK-based fulfilment centres, so they are packed and distributed by it, rather than directly from China.