New York: Facebook Inc. and eBay Inc. removed dozens of groups offering fake and misleading online reviews, after the UK’s antitrust regulator stepped up its crackdown on the online platforms.

The Competition and Markets Authority said Facebook shut down 188 groups with many consisting of people and businesses offering to write misleading reviews on shopping and review websites, while eBay banned 144 users. The action came after the CMA demanded changes from the sites to prevent fake and misleading online reviews from being bought and sold.

Facebook is also testing automated monitoring systems to allow it to detect sites offering fake reviews and remove them promptly, the CMA said in a statement on Wednesday. Both companies fully cooperated, the regulator said.

The crackdown took place following a warning last year by the CMA, which has so far taken the main role in the UK in overseeing the social media giants. The regulator has floated several options to roll back the dominance of the largest tech firms in the online advertising market, including curbing Facebook’s ability to block rivals from using certain features.