The Spotify application is seen on an iPhone in this photo illustration.

Apple will reportedly be hit with a formal investigation in the next few weeks over Spotify's antitrust complaint.

The EU competition authority has decided to launch an antitrust probe into Apple's conduct after considering the complaint and surveying customers, rivals and others in the market, the Financial Times reported, citing three unnamed sources.

Spotify filed a complaint with the European Commission's antitrust regulators earlier this year, alleging Apple Music gives the U.S. tech giant an "unfair advantage" over rivals.

The claim centers around Apple charging a 30% fee on developers for in-app subscription purchases made through the App Store. The firm says those fees make it nigh impossible to keep its prices competitive with Apple Music.