Apple is saying that if publishers want to sell digital newspapers and magazines for the iPhone and iPad, they must give customers the option of paying through its iTunes store.
Apple Inc. receives a 30 percent cut from such sales. If people choose to leave the app anyway and buy through a Web browser, Apple does not receive any of the proceeds. That option will remain available.
News Corp. unveiled The Daily, the first iPad-only newspaper, this month. People are charged through iTunes for a subscription.
Apple recently rejected Sony Corp.'s e-book reader app for the iPhone because it doesn't give people the chance to buy books without leaving the app for a website.