Facebook is still being used by people arranging fake five-star reviews for products, consumer group Which? has said.

It found 14 groups centred around trading reviews for cash or free products – including earbuds, fitness watches and a solar-powered sprinkler.

Which? first reported on such groups in 2018 – and the government is preparing legislation to tackle the problem.

Facebook said it was investing in new technologies to weed out fake reviews.

"Fraudulent and deceptive activity is not allowed on our platforms, including offering or trading fake reviews," said an official from Meta, which owns Facebook.

"We've removed the groups shared with us, for violating our policies."

The Competition and Markets Authority investigated Amazon and Google over concerns fake five-star reviews could be misleading shoppers in 2021.

Then, in April 2022, the government proposed new rules, including making it "clearly illegal" to pay someone to write or host fake reviews.

It says the average UK household spends about £900 each year after being influenced by online reviews.

The new rules are expected to form part of the Digital Markets, Competition and Consumer Bill, due to be published in the coming weeks.

Which? said researchers had found 14 Facebook groups offering cash or products in exchange for reviews on Amazon, Google or Trustpilot.

In total, there were more than 62,000 members across the groups.

When a researcher had contacted a member of one of the most popular groups and told them they liked some of the products shared there, Which? said, they had been told to buy one of the products and they would be refunded if they gave it a five-star review.

"Despite previous interventions by the regulator, our latest findings suggest an industry dedicated to fake-review trading continues to thrive on Facebook," Which? policy and advocacy director Rocio Concha said.

"[It leaves] consumers exposed to misleading information on some of the world's biggest review and shopping platforms."

Amazon has long combated fake reviews on its platform and, in July, took legal action against the administrators of more than 10,000 Facebook groups.

An Amazon official said "in the last few weeks" it had launched further legal action against more than 20 websites dealing in fake reviews.

"By taking this action against fraudsters, we are going after the source of the problem and shutting down these fake-review businesses," they said.