The European Union wants to assess if Apple, Google, and Microsoft are doing enough to prevent the proliferation of online scams on their platforms. The Financial Times reports that EU regulators are formally requesting information from the three US tech companies under the Digital Services Act regarding their efforts to tackle financial fraud, alongside Booking Holdings, the global accommodation platform that owns Booking.com and other travel sites.

“We see that more and more criminal actions are taking place online,” EU tech chief Henna Virkkunen told the publication. “We have to make sure that online platforms really take all their efforts to detect and prevent that kind of illegal content.”

Regulators will evaluate how Apple and Google are handling fraudulent applications like fake banking apps in their respective app stores, while Google and Microsoft’s search engines will be examined for fake search results. Booking, the only Europe-based company being scrutinized, will be analyzed over how it handles fake accommodation listings. These information requests could lead to official investigations being launched into the four companies, which would leave them faced with potential fines of up to six percent of their annual global turnover.