One of the nation's biggest on-line marketplaces is flooded with fake reviews for products, according to a respected consumer champion.

As online retail has continued to grow in importance so too have on-line reviews from customers. But are they real customers?

According to the publication Which?, a champion of consumer rights and standards, the internet retail giant Amazon is awash with "potentially fake reviews".

Items most affected, according to Which?, are products by unfamiliar brands.

"Ninety seven per cent of shoppers rely on online customer reviews to help make a purchase, according to a survey we conducted in September 2018 of more than 2,000 adults.

"The CMA estimates that £23 billion a year of UK consumer spending is potentially influenced by online reviews," said Which?

"This makes fake reviews a serious problem - at best they could mislead you into buying a product that's not as good as it appeared, at worse you could end up with something that's not even fit for purpose."

Which? said 'household name' brands were largely absent from the top-rated reviews of popular items such as headphones - the worst offender by far, apparently - to cameras, fitness trackers and smart watches.

Many of the reviews, it said, were unverified which meant there may be no evidence the commentator had bought the products.

"It took just a couple of hours to uncover more than 10,000 reviews from unverified purchasers on just 24 pairs of headphones - an easy-to-find red flag that highlights the scale of Amazon's problem with fake reviews," said Which?.

"Within these products, we saw numerous instances where hundreds of five-star, unverified reviews arrived on a product listing on the same day, or in a short space of time."

Concern over potentially fake on-line reviews has led the British Standards Institute (BSI) to create a voluntary standard it wants businesses to take on board to help ensure customers are not misled.

Amazon told Which? it invested "significant resources to protect the integrity of reviews".

"Even one inauthentic review is one too many. We have clear participation guidelines for both reviewers and selling partners and we suspend, ban, and take legal action on those who violate our policies," it told Which?.