Book publisher Penguin Group has made electronic versions of its books available again for lending on Amazon’s Kindle via public libraries in the U.S., at least through the end of the year, after previously having the digital books removed from library sites over security concerns.

The episode illustrates the discomfort among major publishers with some of the new distribution channels that Amazon is using for Kindle books.

The catalog of Kindle books available for lending from the Seattle Public Library, for example, is now back to nearly 28,000 titles, after dipping below 23,000 when Penguin briefly withdrew from the program.

PC Magazine reports that Penguin’s security concerns involves making sure that the books are adequately protected from behind the firewalls of ebook suppliers.

“Amazon has undertaken to work with Penguin and Overdrive between now and the end of the year to address Penguin’s concerns,” Penguin said in a statement to the publication. “Penguin will, as a result, restore the supply of these titles until the end of the year in order to return the availability of older titles to all its digital customers.”

Overdrive, which powers the Kindle public library lending service, said in a post that future Penguin titles will remain unavailable while the concerns are addressed.

Amazon launched the public library lending program in September.

Separately, the Seattle company this month announced a Kindle Owners’ Lending Library, allowing Amazon Prime subscribers to check out a book per month from a more limited catalog, without the participation of Penguin or other major U.S. book publishers.

Like what you're reading? Subscribe to GeekWire's free newsletters to catch every headline

Job Listings on GeekWork

Find more jobs on GeekWork. Employers, post a job here.