An Irish data regulator is investigating whether Google secretly uses hidden web pages to track and feed its users’ personal data to advertisers, the Financial Times reports. In a lawsuit, Brave, a small web browser rival to Google, has accused the tech giant of “exploiting personal data without sufficient control or concern over data protection.” If true, the secret tracking would undermine Google’s own policies and break EU privacy regulations. The investigation will determine whether Google uses information such as race, health, and political leanings of its users, to target its ads, according to the FT.

Johnny Ryan, Brave’s chief policy officer, told the regulator that he monitored how his data was being traded on Google’s advertising exchange and discovered that hidden web pages fed his information to third-party companies. In September 2018, Google announced that buyers would no longer receive encrypted cookie IDs in bid requests in its Authorized Buyers marketplace, but Ryan said his analysis also found that this practice was still going on. Google denied the accusations to the FT and said it was participating in the investigation. “We do not serve personalized ads or send bid requests to bidders without user consent,” a spokesman said.