The European Commission has launched a fresh antitrust investigation into Amazon, focusing on whether the company gives its own retail business an unfair advantage on its online marketplace. Regulators are examining whether Amazon’s platform rules or commercial practices may distort competition for third-party sellers.

The probe adds to long-running scrutiny of big tech firms in Europe, where officials have pushed for tighter enforcement against companies accused of using their market power to favor their own services. In Amazon’s case, the concern is whether sellers competing on the platform are placed at a disadvantage compared with Amazon’s in-house retail operations.

The investigation is still at an early stage, and the commission has not announced any findings. Amazon will have the opportunity to respond to the concerns as the review moves forward.

The case comes as EU officials continue to test how far major technology platforms can be allowed to control both the marketplace and the products sold on it, a question with broad implications for online commerce across Europe.