Apple has angered developers over its handling of the iPhone App Store.

The company has drawn criticism for rejecting iPhone App submissions which have been classified as "duplicating the functionality" of current Apple products.

The latest incident came from the company's dealings with Nullriver Software, a small firm whose line-up includes applications that allow Mac users to connect their computers to various games consoles and entertainment systems.

Nullriver had developed a piece of software called NetShare which performed a "tethering" process in which the iPhone's wireless internet connection could be shared with another system.

The company claimed on its site that, after initially removing the application from the App Store on 1 August, Apple declared on 13 September that it would permanently bar NetShare from the store.

"We are seeing a lot of similar reports from various developers whose applications were abruptly removed and banned from the App Store without any violations of the terms of service," Nullriver said. "This is unfortunate news for iPhone end-users."

NullRiver is not the only company being left out in the cold. Apple has refused to carry novelty applications such as the $999 'I am rich' or the gas-passing simulator 'Pull My Finger'.

Now, however, developers are claiming that their applications are being taken down simply for behaving too much like Apple products.

Among the other applications which have been removed from the store is Podcaster, a tool which allows the iPhone to automatically download podcasts.

Podcaster's developer said in a blog posting that Apple had pulled the application for performing the same function as iTunes.

"Although my app does allow you to listen to podcasts (like iTunes), it also allows you to download them directly to device and that is something Apple does not offer," the developer claimed.

"I followed all the guidelines and made sure everything is in the correct place. Yet Apple denies me because I allow users to download podcasts just like iTunes."

Apple has long been hesitant about opening up the iPhone to developers. The handset was restricted to browser-based applications for much of its early life before plans for a Software Development Kit were finally revealed.

Shortly after Apple opened the App Store and released an SDK for developers, the company admitted to placing controls on the phone which would allow the company to remotely remove software deemed harmful.

That list has not yet been populated with any names, however, and the company has vowed that it is strictly a security precaution to prevent data theft.