Sony is throwing its support behind search giant Google's proposed book settlement with author and publisher groups, putting it at odds with Amazon.com, Microsoft, and Yahoo!, which recently joined an alliance opposing the deal. With Sony and the others taking sides, the book settlement -- which underpins Google's project to put millions of scanned books online -- is poised to become a "proxy war" between the world's biggest technology companies over electronic books, Bloomberg reports.

A Sony lawyer indicated the company's support for Google's book settlement in a court filing yesterday, according to Bloomberg. The complex settlement, which would end a 2005 class action lawsuit, must still be approved by a federal court and regulators. Sony didn't immediately respond to a request for comment.

Sony has line of electronic book readers that compete with Amazon's Kindle, and it offers digital versions of more than a million free public domain books scanned by Google. Barnes & Noble has also tapped Google Books for its digital offerings.

Google's scanned books are primarily older, out-of-print titles scanned from major libraries, but the company has also hinted at letting publishers sell new-release digital books through its search engine. That would be a big threat to Amazon, which puts an emphasis on new releases and bestselling titles for Kindle. Amazon has dominated the early market for electronic books.

Google also this week adopted the open ePub format for electronic books, joining Sony, which embraced ePub earlier this month. The open format, which allows for reading across multiple devices, represents a challenge to Amazon, which has a proprietary e-book format for its Kindle readers.

Follow my updates on Twitter.