(AP) -- Apple Inc. has rejected Sony Corp.'s e-book reader app for the iPhone because it doesn't give people the choice to buy books without leaving the app for a website.
The high-profile rejection shows Apple tightening control both over the way apps work and the way money flows through them.
Apple keeps a close eye on the iPhone and iPad programs that outside developers submit for distribution in the iTunes store. Sony's Reader for iPhone app would have sent people to a website once they were ready to buy a book.
Apple's insistence on an in-app purchase option can be seen as its way of ensuring that people using its gadgets get a familiar experience every time they make a purchase through an app. But such a move would prove less lucrative for companies such as Sony, because Apple takes 30 percent cut of revenue from in-app purchases.
In the past, Apple has not enforced this rule across the board. Amazon.com Inc.'s Kindle e-book reading apps for iPhone and iPad don't use in-app purchases, but rather send users to a website.
Sony protested what it calls a change in the way of enforcing the rules.
"We opened a dialogue with Apple to see if we can come up with an equitable resolution but reached an impasse at this time," the company said in a statement.
Apple said this in-app clause was already part of the developer guidelines.
"We are now requiring that if an app offers customers the ability to purchase books outside of the app, that the same option is also available to customers from within the app with in-app purchase," said spokeswoman Natalie Harrison.
Harrison declined to comment on whether Apple would consider removing Amazon's Kindle apps from its store.
Amazon also declined to comment.
Explore further: Encryption made easier: Just talk like a parent