Facebook has sued two app developers for click injection fraud, claiming the developers made Google Play apps that installed malware on a user’s phone for the purpose of generating fake clicks on Facebook ads. That fraudulent ad revenue in turn went to the app developers, Hong Kong-based LionMobi and Singapore-based JediMobi.

Facebook also said LionMobi advertised its malicious apps on Facebook, which is in violation of its policies. The company says its lawsuit is “one of the first of its kind against this practice,” but Google has increasingly taken action against Play Store apps using click injection schemes as well. In October, Google removed more than 30 apps using ad fraud schemes that were reported to the company as part of a BuzzFeed News investigation.

Facebook says it banned the developers from its ad network and refunded impacted advertisers back in March 2019. Apps with millions of installs from both developers could be found on the Google Play store until Wednesday, when they were banned.

Update, August 7th: This article has been updated to note that Google has now banned the developers from the Google Play store.