A group of Japanese book publishers is taking Apple to task for distributing pirated versions of books by Japanese authors via the App Store. The group claims that despite complaints, books by authors such as Haruki Murakami and Keigo Higashino are still available as unauthorized apps.

"We have no choice but to deem it illegal that Apple Inc distributes materials which clearly violate copyright," the group said in a statement to AFP. "Some of the works have been deleted in response to requests from authors and publishers but a majority of them continue to be illegally distributed."

The incensed group includes the Japan Book Publishers Association, the Japan Magazine Publishers Association, the Electronic Book Publishers Association of Japan, and the Digital Comic Association.

Many e-books were originally distributed as individual apps via the App Store before better alternatives, such as Amazon's Kindle app or the Stanza e-book reader app became popular. Apple introduced its own e-book store and reader app this year when it launched iBooks alongside its iPad tablet.

Though the iBookstore makes a seemingly better option for book distribution than individual apps, there are some advantages to releasing books the "old" way. If the material isn't well suited to the current EPUB format, for instance, a custom app might use custom typesetting, include additional multimedia elements, or facilitate user interaction. The Elements: A Visual Exploration is one popular example of such an app.

Those making pirated copies of e-books also benefit from selling individual apps, though. Selling titles via the iBookstore requires an International Standard Book Number, or ISBN, which can serve as a roadblock of sorts for piracy. An e-book wrapped up as an individual app doesn't require an ISBN, and can be easier to pass off as legitimate.

Apple, for its part, said it is doing its best to respond to complaints of pirated material. "We fully understand the importance of intellectual property including copyright," Apple Japan said in a statement to Japanese media. "We will promptly and appropriately respond to complaints about violation of copyright."

The group of publishers believes Apple can do more, including setting up a special division to proactively identify pirated material. "We would rather sit at the same table with Apple and work together to set new rules in the era of digital networks," the group said.