The Competition and Markets Authority said it has launched investigations into Autotrader, Feefo, Dignity, Just Eat and Pasta Evangelists as part of its crackdown on fake and misleading reviews.

Since April last year, companies have been banned from certain tactics around online reviews under law, such as fake posts, paid-for reviews that are not clearly marked as incentivised, as well as for hiding negative feedback.

The CMA said it had launched probes against the companies to see whether consumer laws have been broken.

Sarah Cardell, chief executive of the CMA, said: “Fake reviews strike at the heart of consumer trust – with many of us worrying about misleading content when looking at reviews online.

“With household budgets under pressure, people need to know they’re getting genuine information – not reviews or star ratings that have been manipulated to push them towards the wrong choice.

“We’ve given businesses the time to get things right. Now we’re deploying our new powers to tackle some of the most harmful practices head on.”

The CMA is concerned online reviews play a significant role in people’s decisions, influencing billions of pounds of UK spending every year.

Research from Which? found that 89 per cent of people use reviews when researching a product or service – making it essential that the information they rely on is genuine and transparent. Research published by Truth Engine also suggests that up to half of all online reviews are fake.

Online motor platform Autotrader is being investigated for potentially not counting some one star reviews towards overall star ratings. The CMS said one star reviews, which were moderated by reviews platform Feefo, were not published on Autotrader’s platform, and may not have been counted towards star ratings, therefore denying consumers a fully rounded picture of other customers’ experiences.

Funeral firm Dignity is being investigated for possibly asking staff to write positive reviews about the company’s crematoria services – giving people a potentially inaccurate picture of genuine customers’ feedback.

Takeaway giant Just Eat is being investigated to see if it has been inflating certain restaurants’ and grocers’ star ratings – giving consumers a potentially misleading picture of quality when choosing where to order.

The CMS is also investigating Pasta Evangelists for possibly offering customers discounts on future orders in exchange for leaving 5-star reviews on delivery apps, without this being disclosed – meaning people may not have known how reliable or representative those ratings were.

While the CMA is investigating these five businesses, it has not reached any conclusions about whether consumer law has been broken.

A Just Eat spokesperson said: “We are working closely with the CMA to ensure the reviews and ratings on our platform are clear, transparent and easy to use for all our customers and partners.”

An Autotrader spokesperson said: “We endeavour always to operate as a responsible and compliant business and will co-operate fully with the CMA’s investigation.”

Feefo said: “We remain entirely confident in our compliance frameworks and look forward to contributing to the CMA’s work.”

Pasta Evangelists said it was “co-operating fully with the CMA as it works to understand the facts and the CMA has itself made clear that no conclusions have been reached”.

Dignity said the investigation related to its crematorium and memorial group division and that it was “committed to ensuring full compliance with consumer law and will continue to engage constructively with the CMA”.