The European Commission is investigating whether Germany, Britain, France, Italy and Spain illegally supported soccer clubs by devoting state finances to soccer stadiums, a spokesman for the EU regulatory body said Monday. The probe, which is meant to ensure the soccer industry obeys EU competition rules, follows a series of breaches of EU regulations by European soccer clubs. "It's a core economic activity which is causing a lot of complaints and which we need to pursue," spokesman Tilman Lueder said at a Brussels briefing. The investigation hadn't yet reached any conclusions, he said. Italy was required to change its accounting rules for professional sports clubs in July after the Commission discovered soccer clubs were writing off players' salaries. Real Madrid may have to repay part of the €500 million ($607 million) it earned from selling its training field to the local government if the antitrust regulators determine it violated EU regulations, Bloomberg reported.