UK shoppers have bought an estimated 80 million items on the basis of positive online reviews only to be disappointed when they arrive, National Trading Standards (NTS) has warned.

NTS said consumer trust in online reviews is fuelling a surge in criminals using them to sell poor quality goods and services.

More than half of online shoppers (56%) use online reviews as a deciding factor when buying a product or service and 67% are more likely to buy a product or service if it has a five-star rating, a survey for NTS suggests.

Fake online reviews are estimated to potentially influence £23 billion of UK consumer spending every year, according to Government figures.

However, NTS found just one in five check the timing and spacing of reviews online – if lots of similar reviews have been posted in a short space of time, they may have been submitted by the same person or group – while only 18% look at reviewers’ activity history, which can provide useful information about whether they are genuine.

Some 97% of shoppers using online reviews do not use browser plug-ins such as Fakespot and ReviewMeta to detect bogus reviews.

The Competition and Markets Authority (CMA) is currently leading an investigation into fake reviews, which includes a formal probe into Amazon and Google over concerns they have not been doing enough to combat fake reviews on their sites.

It follows action taken by the CMA last year over the trading of fake reviews, which resulted in Facebook, Instagram and eBay removing groups and banning individuals for buying and selling fake reviews on their sites.

NTS eCrime team national co-ordinator Mike Andrews said: “Bogus online reviews damage legitimate businesses and prop up those seeking to make a fast buck by selling shoddy goods.

“Many of those we surveyed said they felt deceived, conned and tricked after unwittingly falling for the fakes, often only realising the reviews were suspicious when it was too late.

“We urge those doing their Christmas shopping online to look out for fake online reviews and avoid being left out of pocket by using our tips.”

Consumer minister Paul Scully said: “Last summer we published our plans to make fake reviews illegal, and I encourage shoppers this Christmas to follow National Trading Standards’ advice for staying savvy online.”

CMA senior director of consumer protection George Lusty said: “We know this is a big issue for shoppers, which is why we’re investigating concerns that Amazon and Google have not been doing enough to tackle fake reviews. But if you’re worried about being duped online this festive season, there are steps you can take to reduce the risk.”

Here are some tips from National Trading Standards to avoid falling for fake online reviews:

– Timing and spacing. Check for multiple similar reviews that have been uploaded within a few minutes or hours.

– Reviewer’s history. Check the reviewer’s activity – if an account has been activated recently or has only reviewed a narrow range of products/services, this could indicate suspicious activity.

– Vague language. Legitimate reviews will often be personal and specific to the individual’s experience of using the item, whilst a fake is more likely to be vague, using generic words and phrases such as ‘amazing’, ‘awesome’, ‘buy this product’.

– Can you contact them? If a reviewer is happy to be contacted with questions, and is responsive, it’s a good sign they’re legitimate.

– Use a browser plug-in. They use artificial intelligence to analyse reviews, identify suspicious activity and suggest better alternatives to consumers.

– Look beyond the star rating. Whilst a star rating of 4.5 or 5 can be a good indicator of quality, do not go by this alone. Look at the reviews too and check them against these tips.

Anyone who fears they have been the victim on an online scam should report it to actionfraud.police.uk or by calling 0300 123 2040.

For advice and information call the Citizens Advice scams action service on 0808 250 5050.