Inc joined the opposition to Google Inc's plan to digitize millions of books, saying that the proposed deal would fundamentally change copyright law and violate antitrust law.

Amazon, which scans books after getting permission from the copyright holder, said that the court should reject a settlement between Google and the Authors Guild because the deal would change copyright law by allowing Google to digitize books even if the copyright holder cannot be found, often called orphan works.

The proposed settlement usurps the role of Congress in legislating solutions to the complex issues raised by the interplay between new technologies and the nation's copyright laws, Amazon said in its filing, which was dated Tuesday.

Amazon also argued that the book registry envisioned in the settlement could constitute price-fixing.

The proposed settlement would resolve a lawsuit filed in 2005 by the Authors Guild. The Guild and a group of publishers had alleged copyright infringement.

Google has agreed to pay $125 million to create a Book Rights Registry, where authors and publishers could register works and receive compensation.

Under the settlement, authors have until the end of this week to tell Google that they do not want their books digitized. A hearing on approval of the settlement is set for October 7 in Manhattan federal court.

Google rejected the criticisms.

The Google Books settlement is injecting more competition into the digital books space, so it's understandable why our competitors might fight hard to prevent more competition, said Google spokesman Gabriel Stricker in an email.

It's important to note that this agreement is non-exclusive and if approved by the court, stands to expand access to millions of books in the U.S.

Google's rivals, Microsoft Corp and Yahoo Inc, also oppose the plan, while the American Library Association and Association of Research Libraries have asked for court oversight. They fear that if the service becomes a necessity for libraries, they would face monopoly pricing.

The U.S. Justice Department is investigating the deal while European Union antitrust enforcers, prompted by Germany, have said they would study it.

The case is Authors Guild et al v Google Inc 05-08136 in U.S. District Court for the Southern District of New York (Manhattan)

(Reporting by Diane Bartz; Editing by Gerald E. McCormick and Richard Chang)