The announcement by the European Commission follows problems for Amazon and other United States technology companies in Europe as policy makers pursue a series of tax, antitrust and other investigations into businesses of Apple, Google and Facebook.

Attention has particularly focused on Amazon, the region’€™s largest e-commerce company. The company’€™s complex tax practices in Luxembourg, home to its European headquarters, are the subject of a separate investigation by the European authorities.

The European Commission, the executive arm of the European Union, is also pursuing an antitrust investigation into whether large tech companies have impeded competition in the region’s online shopping industry.

As part of this latest investigation, the commission said it was evaluating the legality of clauses that Amazon had used with European publishers, which required them to inform the e-commerce giant of more favorable terms for books that were offered to other digital retailers.

The European authorities said these clauses may have hampered competition in the e-book market by making it more difficult for Amazon’€™s rivals to offer lower prices.

Antitrust officials added, however, that the opening of the investigation did not yet indicate that Amazon had broken the region’€™s competition laws.

“Amazon has developed a successful business that offers consumers a comprehensive service,”€ Europe’€™s antitrust chief, Margrethe Vestager, said on Thursday in a statement. “€œIt is my duty to make sure that Amazon’€™s arrangements with publishers are not harmful to consumers, by preventing other e-book distributors from innovating and competing effectively with Amazon.”€

In a statement on Thursday, Amazon said it was “€œconfident that our agreements with publishers are legal and in the best interests of readers.”€ The company said it would “€œcooperate fully during this process.”€