Sony Electronics Inc. is joining forces with Google Inc. to battle Amazon.com Inc. in the growing electronic books market which is projected to more than double this year.

Google is making half a million books from its book digitization project, unprotected by copyright, available for free on Sony's electronic book-reading device via the online Sony eBook store.

The move catapults the Sony Reader past Amazon.com's Kindle as the device with the largest available library, as it will now have around 600,000 titles. Currently, Amazon's library offers 250,000 titles for Kindle.

The companies did not reveal financial terms of the deal.

This is the first time that Google has made its extensive library of scanned books available on an e-book reader. Google had started scanning books from 2004. To date, about seven million ebooks from major universities and libraries have been scanned already.

Sony Reader owners now have access to books written before the year 1923.

The books are already available as free downloads in the Portable Document Format (PDF), which works well on computer screens but not on e-book readers. Google will provide the books to the Sony Reader in the EPUB (electronic publication) format, which lets the lines flow differently to fit a smaller screen.

The Kindle was first introduced in 2007, three years after Sony’s first digital reader. Amazon launched its Kindle 2 last month which retails at $359 and can hold more than 1,500 book titles.

Comparatively cheaper than Kindle, Sony Reader lacks wireless connectivity to connect the device directly to an ebook store.

Sony Google Kindle