Shoppers have been warned about the risk of buying counterfeit goods on Amazon amid claims that the internet retailer is being “plagued” with fakes.

Experts say that the highest risk comes when buying from third-party vendors on Amazon’s marketplace. More than half of Amazon’s sales are supplied by independent retailers, but many shoppers will have no idea they are buying from separate companies.

Increasing numbers of these suppliers sell under the Amazon Prime label, which promises next-day delivery. Often these vendors store their goods in Amazon’s warehouses to ensure the speediest delivery. Amazon makes a commission on every product that third parties sell through its website.