Apple has started to ban many applications for the iPhone that feature sexually suggestive material, but the surprise move has some developers up in arms over a perceived lack of consistency.

The company said it was responding to complaints from users as some software vendors were submitting objectionable content. Developers expressed their discontent as thousands of adult themed apps were removed, while some others, like one from Playboy has remained.

I'm now worried the eco-system is run by puritans and is not fair to all players, developer Jon Atherton said on its website.

Atherton's Australian company, ChilliFresh, created an app that provides pictures of women's breasts that wobble as users shake their phones.

And worst of all it is not a secure source of income. It can drop to close to zero if they decide to change the rules, he added.

Apple said that it was responding to complaints it was receiving from parents and women who found the content too degrading and objectionable. Speaking to the New York Times, Apple's head of marketing Phil Schiller also explained why some were removed while others weren't.

The difference is this is a well-known company with previously published material available broadly in a well-accepted format, Schiller said. Parents were upset with what their kids were able to see.

He also said that the company had been seeing an increasing number of apps with sexually suggestive content in recent weeks.

But Atherton says the apparent bias towards established brands hurts Apple's credibility.

So it's ok for a well known company to produce and display adult material to our children, but not ok for somebody to show cartoon pics of a female body, he wrote.

Atherton and other developers are calling for Apple to publish its new guidelines so that developers were clear on what they could and could not do as well as to clarify why not all sex-related apps are affected by the ban.