The controversy centres on the so-called "agency model" of pricing, which allows publishers to dictate the charge for each ebook as long as the retailer gets 30pc of the profits. Publishers Hachette, HarperCollins, Penguin Group, Simon & Schuster and Macmillan all signed up to the scheme with Apple, before it was adopted by other retailers.
However, the arrangement has sparked controversy and legal battles on both sides of the Atlantic. Last December, the European Union opened an investigation into anti-competitive behaviour. In America, the Department of Justice (DoJ) has launched legal action against Apple and the publishers for alleged collusion.
The technology company was initially tight-lipped about the US case but last week broke its silence to declare itself innocent and paint itself as a hero for breaking Amazon's "monopolistic grip". It said the iPad's bookstore "fostered innovation and competition".
However, it has taken an altogether different approach in Brussels. Joaquín Almunia, the European Union competition commissioner, said he has received settlement offers from Apple and all the publishers other than Penguin.