Smoke alarms that do not work and USB chargers that could cause fire have been found among a mass of unsafe products available through popular shopping websites.
Which? and consumer groups across Europe tested 250 products from online marketplaces including Amazon Marketplace, eBay, AliExpress and Wish and claim two-thirds failed EU safety requirements.
Researchers say they found safety flaws in everything from toys and children’s clothing, to jewellery and cosmetic products, being sold by third-party sellers.
These included Christmas lights that could give an electric shock and a power bank that melted during testing.
All of the products selected for examination in the teeth-whitening, carbon monoxide alarm, balloon, smoke alarm and helmet categories were deemed safety failures.
Despite online marketplaces removing the dangerous items after being informed of the issues, some reappeared soon after.
Which? is calling on the Government to make online marketplaces legally responsible for ensuring the safety of products sold on their sites.
“Online marketplaces have quickly become a popular way for people to shop online and yet Which? testing has repeatedly exposed how large numbers of dangerous products are sold on these sites every day,” said Neena Bhati, head of campaigns at Which?.
“These platforms have failed to get a grip on this despite years of warnings, and so the Government must now step in to make online marketplaces responsible for ensuring the safety of the products sold on their sites.”
Amazon, AliExpress, Ebay and Wish each responded saying they take safety seriously on their platforms.
“These are isolated incidents that do not reflect the fantastic products and customer experience provided by millions of small businesses selling in our store,” Amazon said.
Ebay responded saying between October 2018 and October 2019 filters automatically blocked five million listings from entering the marketplace on product safety grounds.
“We have no tolerance for unsafe, banned, recalled, or illegal products on our marketplaces, and it is required in our User Agreement that all sellers comply with the law,” the firm said.
A spokesman for the Office for Product Safety and Standards said: “The Government’s top priority is to keep people safe, which is why the UK has some of the strictest product safety laws in the world.
“We’ve written to all major online retailers asking them to explain the steps they are taking to ensure dangerous products are not for sale on their sites.”