* Hachette operating in 'good faith' but two sides at odds -Amazon
* Affected Hachette titles can be bought from third-party sellers (Adds comments from Amazon, background on dispute)
By Deepa Seetharaman
SAN FRANCISCO, May 27 (Reuters) - Amazon.com Inc is preparing for a long battle with Hachette Book Group over a contract dispute that led the U.S. online retailer to curtail sales of some of the publisher's books.
In a statement on Tuesday, Amazon said Hachette, a unit of French media company Lagardere SCA, has operated in "good faith" but the two sides remain at odds. The comments, the first by Amazon since the dispute became public in early May, didn't disclose details of the disagreement between the pair.
"Though we remain hopeful and are working hard to come to a resolution as soon as possible, we are not optimistic that this will be resolved soon," Amazon said in a statement posted online. [link.reuters.com/zum69v ]
Hachette didn't immediately respond to an email seeking comment outside of regular business hours.
Amazon has been buying fewer print books from Hachette and last week removed an option to pre-order Hachette titles that will be published in the future. These include "The Silkworm", an upcoming novel written by author of the Harry Potter series J.K. Rowling, under the pen name Robert Galbraith.
In recent weeks, authors and other publishing insiders have criticized Amazon for unfairly wielding its power as a major retailer to gain an edge in contract talks.
"What I don't understand about this particular battle tactic is how it is in the best interest of Amazon customers," author James Patterson said in a May 13 post on his Facebook page.
In a letter to authors posted on May 23 on the website of the Authors Guild, a group for book authors, Hachette chief executive Michael Pietsch said the publisher was looking for a solution "that preserves our ability to survive and thrive as a strong author-centric publishing company."
In its statement on Tuesday, Amazon said customers looking to buy one of the affected titles should "purchase a new or used version from one of our third-party sellers or from one of our competitors."
The company said it would put up half the money for a fund to help offset the loss in royalties to Hachette authors as a result of the disagreement if Hachette pays for the other half.
Amazon has a record of being involved in combative negotiations. In 2010, the company blocked consumers from buying works published by Macmillan in a dispute over the price of e-books.
"When we negotiate with suppliers, we are doing so on behalf of customers," Amazon said in its statement. "Negotiating for acceptable terms is an essential business practice that is critical to keeping service and value high for customers in the medium and long term." (Reporting by Deepa Seetharaman; Editing by Lisa Shumaker, Christopher Cushing and Kenneth Maxwell)