This Friday music streaming service Spotify confirmed that it had filed a complaint with Apple Inc. (NASDAQ:AAPL) over the tech giant’s policy on its App Store.

Apple Inc. (NASDAQ:AAPL) rejected an updated Spotify app for iPhone users in a move which the music streaming service says is causing it “grave harm.”  The move is especially controversial given the fierce competition between the two companies in the music streaming market, writes Mia Shanley for The Huffington Post.

Spotify Goes To War Against Apple Inc. (AAPL)

Spotify not happen with Apple (AAPL) over app rejection

Spotify has been offering music streaming for years, while Apple Music launched last year in over 100 countries. The rejection of the new app sparked a complaint letter that was sent to Apple Inc. (NASDAQ:AAPL)’s lawyer this week.

According to the letter the rejection of the revised app provoked “serious concerns” under U.S. and European competition law. It was responsible for causing “grave harm to Spotify and its customers.”

“It continues a troubling pattern of behavior by Apple to exclude and diminish the competitiveness of Spotify on iOS and as a rival to Apple Music,” a report in Recode quoted Spotify general counsel Horacio Gutierrez as saying in the letter.

“We cannot stand by as Apple uses the App Store approval process as a weapon to harm competitors,” Gutierrez said. The report has been confirmed as accurate by a spokeswoman for the company.

Music streaming a crowded sector

Since its launch ten years ago Spotify has become the biggest paid music streaming service in the world, with around 30 million paying users in 59 markets. In comparison Apple Music has around 13 million.

The Swedish company said that Apple Inc. (NASDAQ:AAPL) rejected the revised app under “business model rules.” The U.S. tech giant apparently said that it would have to use Apple’s billing system if it aimed to “use the app to acquire new customers and sell subscriptions.”

The music streaming business has become increasingly crowded, with Alphabet’s Google Music and YouTube also competing with Spotify and Apple Music. Smaller competitors include Pandora Media Inc and Tidal, run by rapper Jay Z.

Sources have reportedly also told Reuters that Amazon.com Inc is working on a music streaming service. Those interested in the music streaming sector should keep an eye on how this story develops as it could have serious implications for the business.