BERLIN (Reuters) - The German antitrust authority has notified Apple ( AAPL ) of concerns regarding the iPhone maker's app tracking tool, which could violate rules for large tech companies, the regulator said in a statement on Thursday.

The Federal Cartel Office's preliminary assessment follows a three-year investigation into Apple's ( AAPL ) App Tracking Transparency feature, which allows users to block advertisers from tracking them across different applications.

"Apple ( AAPL ) now has the opportunity to respond to the allegations," the office said.

The U.S. tech giant has said the feature allows users to control their privacy but has drawn criticism from Meta Platforms ( META ), app developers and startups whose business models rely on advertising tracking.

(Reporting by Rachel More in Berlin and Foo Yun Chee in Brussels, editing by Thomas Seythal)