Google asked a US court Friday to put an end to a long-running lawsuit over the Internet giant's massive book-scanning project, saying the effort is "not a substitute" for books themselves.

The US tech giant offered its defense by arguing that its Google Books project should be considered "fair use" under copyright law, and said the judge should rule in its favor.

"Google Books gives people a new and more efficient way to find books relevant to their interests," the company said in its petition for summary judgment in the case in a New York federal court.

"The tool is not a substitute for the books themselves -- readers still must buy a book from a store or borrow it from a library to read it. Rather, Google Books is an important advance on the card-catalogue method of finding books."

Google said the effort is beneficial to readers, authors and the public.

"Readers benefit by being able to find relevant books," Google argued. "Authors benefit because their books can be more readily found, purchased, and read. The public benefits from the increase of knowledge that results."

Google has scanned more than 20 million books so far in the project. Books in the public domain -- without current copyrights -- are made available online to the public for free. For copyrighted books Google offers a searchable database that displays snippets of text.

The Authors Guild and the Association of American Publishers filed the suit in 2005 alleging copyright infringement.

A tentative settlement in the case was reached in 2008 under which Google would pay $125 million to resolve copyright claims and to establish an independent "Book Rights Registry." But a judge rejected the deal.

Opponents of the agreement have said allowing Google to proceed with the project raises anti-trust, privacy and copyright issues, while also granting sole rights to Google to digitize millions of out-of-print works whose authors cannot be traced.

Others say copyright cannot be waived unless an author expressly opts out of the deal.

Google said in its argument, however, that copyright is not absolute, and that numerous fair uses exist under the law.

"The purpose of Google Books is to help users find books that are of interest to them," it said. "Research and scholarly uses range from literary research to helping fifth-graders find books for their book reports."

A Google spokesman said: "We believe Google Books constitutes fair use by allowing users to identify interesting books and find ways to borrow or buy those books, much like a card catalog for the digital age."

Plaintiffs in the case are to file replies by August 24, and Judge Denny Chin is scheduled to hear arguments October 9 on whether to proceed.