Apple blocks Sony eReader app
The move comes as the company attended the launch of News Corp's Daily magazine in New York this morning.
Steve Haber, the head of Sony's digital reading division, told the publication that in-app purchases now have to be made through Apple.
"It's the opposite of what we wanted to bring to the market," Haber said. "We always wanted to bring the content to as many devices as possible, not one device to one store."
Apple spokesperson Trudy Muller said that while the developer terms and guidelines haven't changed, if apps have the ability to purchase books outside of the application itself, they also need to offer that option in the app too.