Sony Corp is making available public domain books from Google Inc to users of its electronic book reader, Sony said on Wednesday, vastly increasing the amount of available content on the device.

In the latest round of a budding digital book battle with Amazon.com Inc, Sony said that more than a half a million classic titles will be free to users of the Reader, which allows consumers to read books and newspapers on a hand-held device.

That will boost the available titles in Sony’s eBook Store to more than 600,000, Sony said.

Sony sells two versions of its Reader, which competes directly with Amazon’s Kindle. Kindle users can access over 245,000 titles plus newspapers, magazines and blogs.