Apple may have locked developers out of one key iPhone element, forbidding third-party applications from accessing iTunes.

This is likely to affect games developers seeking to source sounds from a user's iTunes library, but will have far more effect on social networking music applications such as iLike or Last.FM.

The move will also prevent other music services, such as Amazon or eMusic, from creating applications that will allow iPhone users to purchase music from alternative services to iTunes.

If true, then Apple may face investigation by anti-trust authorities for tying its dominant online music service to its device at the expense of competitors.