Apple along with four other publishers has begun offering retailers with concessions, in an attempt to end an ongoing European Commission anti-trust investigation and avoid heavy fines, which could total up to 10% their global annual revenue, or €13.5bn ($10.8bn).

In 2010, the four publishers, including Simon & Schuster, HarperCollins, Hachette Livre and Holtzbrinck, signed agreements with Apple, which would allow online versions of their books sell for set prices on the iPhone maker’s iBooks, with Apple owing 30% of the proceeds.

The agreements also stated that other retailers, including Amazon, would not be allowed to sell the e-books any lower price.

Further, the EU antitrust regulator had commenced an investigation into Apple’s e-book pricing deals with the publishers during December 2012, claiming that Apple had plotted to fix e-book prices, which may go against competition in Europe.

A source close to the matter was quoted by Reuters as saying, "The Commission is market testing the commitments on an informal basis."

The deals are similar to those reached in the US government price-fixing settlement lawsuit against HarperCollins, Simon & Schuster and Hachette, which also sold their e-books with Apple.

Amazon, which uses the ‘wholesale model’, allowing the retailers pay for a product and charge what they like, had charged $9.99 for its e-books.