BRUSSELS, (Reuters) – EU antitrust regulators have prepared an additional accusation against Apple (NASDAQ;) as part of an investigation triggered in part by a Spotify complaint (NYSE:) as EU enforcers strengthen the case.

Last year, the European Commission accused Apple of monopolizing the music streaming industry through restrictive rules in its App Store. These restrictions force developers to use their own payment method and stop them from informing customers about other options.

When the EU Competition Enforcementr gathers new evidence, or modifies some elements in order to strengthen its case, additional charges are typically imposed to companies.