Apple Inc has blocked rival Sony Corp's electronic book application from the iPhone because it would have circumvented Apple's system for buying content.
The scrap is the latest in Apple's long history of tense relations with media companies. They have clashed for years over pricing and how music, movies and books are sold on Apple's mobile devices, the iPod, iPhone and iPad.
The dust-up, first reported by the New York Times, comes a day before the expected launch of News Corp's The Daily, a subscription digital newspaper designed for tablet computers like the iPad.
Sony's app, which is linked to Sony's e-book reader, would have allowed people to read books bought through Sony's store. Sony accused Apple of changing the way it enforces its rules.
The e-reader episode highlights what publishers in general see as Apple's rigidity.
Richard Stephenson, chief executive of Yudu, an online publishing services company that works with magazines including Readers Digest and small publishers, expects Apple to begin enforcing its payment rules for content more strictly.
"If you're intending to dine with the 600-pound gorilla, then you have to abide by their table manners," Stephenson said. "People are saying that Apple is changing the rules, but in fact they're just enforcing them."
Apple said it was not changing its rules for app developers, but wanted to ensure that customers could buy books using its payment method, known as "in-app purchase," which provides Apple with a 30 percent cut of sales.
Apple's stance did not appear to affect Amazon.com. Amazon did not respond to a request for comment, while its Kindle app for the iPhone, which allows users to access e-books bought through Amazon, was still functioning.
Apple also sells e-books for the iPhone and iPad through its iBookstore.
"We opened a dialogue with Apple to see if we can come up with an equitable resolution for both companies as well as our consumers, but reached an impasse at this time," Sony said in a statement on Tuesday.
Apple's developer guidelines say that apps using a system other than in-app purchase to buy "content, functionality, or services in an app will be rejected."
Apple requires apps that let customers buy books outside the app to offer the option to buy books through Apple's system, a spokeswoman said.
It is not the first time that Apple's rules for app developers have caused controversy.
Apple effectively banned developers from using Adobe Systems' Flash software and other technologies to build apps, before easing the restrictions last year.
Apple last year also relented on restrictions for rival ad agencies on the iPhone that some people called onerous.
Apple does not offer in-app subscriptions for content like newspapers or magazines. Some industry watchers expect the company to announce them at the News Corp event on Wednesday.