Banned ingredients have been found in sweets and drinks sold by Amazon.
Which? discovered jellies made with the thickening agent konjac – banned by the EU because it can cause choking.
And the consumer group said two soft drinks, Fresca Original Citrus and Mountain Dew, were listed by the online giant that contain brominated vegetable oil which is outlawed.
The oil is used to stop ingredients separating in the bottle but can cause headaches, memory loss, and impaired balance.
The items were on Amazon Marketplace which offers goods from so-called secondary sellers, not Amazon itself – and all have since been removed.
Which? has previously found banned and recalled toys for sale via Amazon.
Amazon said: “If customers have concerns about an item, we encourage them to contact our customer service so we can take action.”
Consumer watchdogs who found the products for sale claim Amazon is failing to protect customer safety. They have already criticised the Amazon Marketplace site for selling toys deemed unsafe under EU safety rules.
Marketplace sales offer goods supplied by so-called secondary sellers - rather than Amazon itself. The world’s biggest retail site hosts their listings.
Sue Davies, head of consumer protection at Which?, said: “The Government must make their responsibility clear and ensure that unsafe products, including foods, are prevented from going on sale and swiftly removed if they are found.”
The Food Standards Agency said: “Everyone involved in online marketplace selling - from the host platforms to the seller - must ensure food is safe. We want these companies to take more responsibility for the products sold on their sites.”
All products have since been removed from the site.
Amazon said: “Safety is important to us and we want customers to shop with confidence in our stores. We have proactive measures in place to prevent suspicious or non-compliant products from being listed and we monitor the products sold in our stores for product safety concerns.
“When appropriate, we remove a product from the store, reach out to sellers, manufacturers and government agencies for additional information, or take other actions. I
f customers have concerns about an item they have purchased, we encourage them to contact our customer service directly so we can investigate and take appropriate action.”