Screenshot by Shara Tibken/CNET

iPhone users now have another option for downloading songs from their device.

Amazon today launched its MP3 store for iPhone and iPod Touch users, allowing them to buy digital music from Amazon's 22-million song catalog. There's one catch, though. The purchases have to be made via the Safari Web browser, not through any of Amazon's apps. That means the process isn't quite as seamless as buying music through iTunes.

Amazon noted that music purchases are automatically saved to the customer's Cloud Player library and can be downloaded or streamed instantly from an iPhone , iPod Touch , Kindle Fire, Android phone or tablet, Roku, Sonos home entertainment system, or any Web browser. It also said the MP3 mobile site is built on HTML5 so users can make purchases directly from www.amazon.com/mp3.

"Since the launch of the Amazon Cloud Player app for iPhone and iPod touch, a top request from customers has been the ability to buy music from Amazon right from their devices," Steve Boom, vice president of Amazon Music, said in a statement. "For the first time ever, iOS users have a way do that."

Amazon, Apple, and other companies have been battling over providing consumers with content like music, movies, and books. Amazon is believed to make most of its mobile-related profit from the content it sells rather than from the sale of its devices.

Traditionally, iOS users have been able to access Amazon's apps like Kindle and Cloud Player but haven't been able to purchase items from Amazon on their devices. That's largely because of an Apple rule designed to make sure it gets its 30 percent cut on all sales apps generate.

In the past, e-reading apps Kindle, Nook, and Kobo avoided paying the cut by sending customers to a Web-based interface outside the app. But that changed in mid-2011 when Apple made conditions far stricter.