Brussels: Apple Inc., the world’s biggest technology company, and five e-book publishers are being investigated by European Union (EU) antitrust regulators over deals that may restrict sales across the region.

The probe targets the iPad maker’s deals with Lagardere SCA’s Hachette Livre, News Corp.’s Harper Collins, CBS Corp.’s Simon and Schuster, Pearson Plc’s Penguin and Verlagsgruppe Georg von Holtzbrinck GmbH’s Macmillan division, the European Commission said in an e-mailed statement. Publishers’ deals with retailers are also under scrutiny.

Today’s probe will in particular investigate whether these publishing groups and Apple have engaged in illegal agreements or practices that would have the object or the effect of restricting competition, the Brussels-based authority said. Inc., the world’s largest Internet retailer, may sell as many as five million e-book readers in the fourth quarter, according to a report from Forrester Research Inc. Amazon sold about half of the 12.8 million e-book readers purchased worldwide last year, IDC said in March. E-books are also sold for media tablets such as the iPad and Samsung Electronics Co. Ltd’s Galaxy.

The probe isn’t Apple’s first encounter with the EU’s antitrust authority. The company settled an EU antitrust case in 2009 by agreeing to reduce prices for UK iTunes music downloads and was probed over restrictions on iPhone applications in a case the EU closed last year.

Some European newspapers also protested earlier this year against Apple’s proposed subscription model for the iPad. Apple and Samsung were recently quizzed by the commission over the use of smartphone patents, regulators said last month.

Apple Lagardere declined to comment about today’s EU announcement. Amazon didn’t immediately respond to a call and an email seeking comment. Pearson does not believe it has breached any laws, and will continue to fully and openly cooperate with the commission, the company said in an emailed statement.

Harper Collins is cooperating fully with the investigation,according to an emailed statement from spokeswoman Siobhan Kenny. CBS and its Simon and Schuster unit, and Harper Collins didn’t immediately respond to calls and emails seeking comment. Holtzbrinck didn’t immediately respond to an email query.

Heather Smith in Paris contributed to this story.