The Amazon logo is displayed on a smartphone and a PC screen.

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LONDON – The UK competition authority on Friday opened a formal investigation into Amazon and Google over concerns that they had not done enough to combat fake reviews.

“We are investigating concerns that Amazon and Google have not done enough to prevent or remove fake reviews to protect customers and honest businesses,” said Andrea Cocelli, CEO of the CMA, in a statement.

“It is important that these technology platforms take responsibility and that we are ready to take action if we find that they are not doing enough.”

Misleading customer reviews have proven to be a huge problem in e-commerce, and Amazon is a prime target for brands looking to spice up their products online with fake, cheap write-ups. Last month, the company urged social media firms to weed out dishonest reviews.

The competition and market supervisory authority launched an initial investigation into the problem of falsified reviews in May 2020. Earlier this year, she had Facebook and eBay remove several groups and accounts involved in the fake reviews trade.

Then, in April of that year, the CMA said Facebook removed thousands more groups trading in false and misleading reviews and made further changes to its systems to identify, remove, and prevent such content on its platforms.

On Friday, the CMA focused on Amazon and Google, saying it would look to see if they had done enough to detect and remove fake reviews. The investigation will also investigate whether companies are penalizing appraisers or companies to prevent them from publishing misleading results.

The watchdog added that it was concerned that Amazon’s systems could not prevent sellers from tampering with product lists, citing the example of merchants taking positive reviews of other products.

The CMA has not yet decided whether Amazon and Google have broken the law at the time, but said they would take enforcement action – including legal proceedings against the companies that may become necessary – if they are found to be in breach of consumer law.

“We use significant resources to prevent fake or animated reviews from appearing in our store,” an Amazon spokesman told CNBC.

“We work hard to ensure that reviews accurately reflect customers’ experiences with a product,” added the spokesman.

“We will continue to assist the CMA with their investigations and note their confirmation that no findings have been made against our business.”

A Google spokesman said the company’s guidelines “must clearly be based on real experience”.

“If we discover policy violations, we take action – from removing abusive content to deactivating user accounts,” the spokesman told CNBC.

“We look forward to continuing our collaboration with the CMA to learn more about how our industry-leading technology and review teams are working to help users find relevant and useful information on Google.”

It’s the latest in a string of investigations against digital giants. Just three days ago, the European Union launched another antitrust investigation against Google to investigate whether the internet search giant prefers its own online display advertising technology services.

The British CMA wants to take on a growing role in screening large US technology companies after Brexit. The watchdog has been hired by the government to set up a new Digital Markets Unit to monitor competition in the UK internet market.