Food delivery giant Just Eat and motoring site Autotrader are among five firms being investigated as part of a probe into fake and misleading online reviews by the UK's competition watchdog.

The Competition and Markets Authority (CMA), which is also investigating reviews site Feefo, funeral firm Dignity and Pasta Evangelists, is looking at whether they have broken consumer law.

The investigation will focus on how reviews are obtained, moderated and presented to customers.

Online reviews influence billions of pounds of spending each year, yet many consumers worry about misleading content online.

"Fake reviews strike at the heart of consumer trust," said the CMA's chief executive, Sarah Cardell.

"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."

Under new powers announced in 2024 and enforced since April, the CMA can fine firms for violating consumer law, without needing to go through the courts.

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

The CMA said: