One of the largest publishers in the U.S., Penguin Group, has suspended making e-editions of new books available to libraries and won't allow libraries to loan any e-books for Amazon.com's Kindle e-readers and tablets.

"We have always placed a high value on the role that libraries can play in connecting our authors with our readers," the publisher announced in a statement Monday. "However, due to new concerns about the security of our digital editions, we find it necessary to delay the availability of our new titles in the digital format while we resolve these concerns with our business partners."

For non-Kindle users, the policy does not affect e-books already on library catalogues. Penguin's authors include Patricia Cornwell, Ken Follett and Ron Chernow, and new books include Sue Grafton's V for Vengeance and Rep. Michele Bachmann's Core of Conviction.

The publisher did not cite any specific titles in its release and did not immediately respond to requests from The Associated Press to clarify its security concerns. Among publishers, "security" has traditionally referred to piracy, but this time it likely means Amazon.com's Kindle lending programs.

The online retailer is allowing its special Prime members to rent one book a month from a selection of titles provided by it. Some publishers declined to participate but discovered their books were still being included, a policy denounced as illegal by the Authors Guild, which represents published writers.

Libraries began testing loans of e-books more than a decade ago.Libraries began testing loans of e-books more than a decade ago. Tim Boyle/Newsmakers/Getty Images

Meanwhile, Amazon has formed a partnership with the country's top library e-book supplier, OverDrive Inc., that vastly increases the Kindle's presence in libraries and encourages patrons to visit Amazon's website and buy books.

OverDrive posted a statement on its website that it had been asked by Penguin to "disable the 'Get for Kindle' functionality for all Penguin e-books."

Besides being worried about Amazon's power in the digital market, publishers have long been concerned that allowing library patrons to download e-books might harm sales. Simon & Schuster and Macmillan don't make any e-books available to libraries, and HarperCollins has restricted their usage, a policy that angered libraries when announced last year.

OverDrive CEO Steve Potash said Monday that his company and Penguin were "in the process of looking at new terms" for libraries but declined to say what the terms were.

While borrowing e-books from libraries has become more difficult, buying books — Penguin's included — through libraries is becoming easier. Starting Monday, patrons using the New York Public Library's website who wish to purchase a title can click a Buy it Now tab that links to participating sellers. The library receives a portion of the proceeds, and Potash said he expects the program will soon expand nationwide and into Canada and the United Kingdom.

Sellers involved so far are Barnes & Noble; BooksOnBoard, an independent e-store; and Amazon.