A defect of the eBay platform allows positive reviews on genuine products to be shared on potentially unsafe and counterfeit goods.

Campaign group Which? found that by using the same product ID as other goods, glowing reviews can be lifted on to the inferior goods posted by unscrupulous sellers.

This makes it difficult for shoppers to tell which items are the real thing. The research tracked hundreds of listings including chargers, charging cables, headphones, smoke alarms and travel adaptors.

It found counterfeit Samsung chargers that had been recalled were still being listed with 4* and 5* reviews.

Researchers also ordered 20 supposedly official Apple and Samsung accessories and despite being listed by different sellers, they all shared the same reviews.

As well as the product ID flaw, Which? found gaps such as sellers being able to leave reviews for their own products – a practice banned by other online marketplaces including Amazon.

Which? said eBay must take urgent action to make its review system more robust and transparent, so that consumers can trust the customer feedback on products they are buying, particularly as an estimated £23bn a year of consumer transactions are influenced by online reviews.

Natalie Hitchins, head of home products and services at Which?, said: “Our investigation has uncovered yet another example of online reviews being manipulated to mislead people. eBay’s product review system is confusing for consumers and could even direct them towards counterfeit or dangerous products sold by unscrupulous sellers.

“Online reviews influence billions of pounds of consumer spending each year. The CMA must now investigate how fake and misleading reviews are duping online shoppers, taking the strongest possible action against sites that fail to tackle the problem.”

An eBay spokesperson, said: “We have investigated the listings shared by Which? and will remove any that breach our policies.

“However the research does not fully consider there are distinctions between product reviews (which provide buyers with a holistic review of the same product), and seller feedback (which can be used to see specific reviews of a seller’s performance and may reflect the item’s condition).

“All listings have a ‘report’ feature. Any user can use this to report a concern with a listing, its seller, or its reviews.

“We take enforcement action against any seller found to be in breach of our policies, which can be in the form of a warning, suspension or ban.”