More than one million households in the UK may have fallen victim to a scam known as “brushing” after receiving Amazon parcels they did not order.
Growing numbers of people have reported being sent unsolicited packages to their homes which arrived with no return addresses.
The parcels included magnetic eyelashes, children’s toys, Bluetooth accessories, iPhone cases and medical gloves.
Now consumer group Which? has said the mail-outs are part of a ruse in which third-party sellers from overseas are attempting to boost their standing on Amazon’s ultra-competitive search ranking system.
The sellers send out the unwanted products and log it as a genuine purchase because the more transactions they appear to make, the higher they rise up the ratings.
But, while the scam does not appear to cost recipients anything, it does raise questions about how their personal details were found.
There are also concerns over the fact sending out hundreds of thousands of unwanted consumer goods will have considerable environmental implications.
A survey of almost 2,000 people by Which? found that four per cent of respondents - or, scaled up nationally, an estimated 1.1 million people - said they or someone in their household had received such a package.
Of the respondents who received a mystery parcel, 63 per cent said they kept them, 28 per cent threw them away and 16 per cent gave them away.
Rocio Concha, director of policy and advocacy for the watchdog, said: “Consumers should be able to trust that the popularity and reviews of products they are buying online are genuine, so it is troubling that third-party sellers appear to be using brushing scams to game Amazon Marketplace.
"Amazon needs to do more to thoroughly investigate instances of brushing scams and take strong action against sellers that are attempting to mislead consumers."
Amazon said brushing was a scheme affecting all online marketplaces.
A spokesperson said: “We estimate that less than 0.001% of Amazon orders are impacted by brushing as Amazon has robust processes in place to prevent abuse from impacting our reviews, search rankings and other customer experiences.”
But they added: “We will never stop improving the sophistication of abuse prevention in our store, and we will continue to take the appropriate enforcement actions, including support for law enforcement organisations in their efforts to hold bad actors accountable.
“We strongly encourage those who have received unsolicited packages to report them to our customer services team so that we can investigate fully and take the appropriate actions."