Sony says content for its Reader digital book "just blew wide open" with the news that eBook Store from Sony will provide access to more than half a million public domain books from Google optimised for current models of the Reader.

Sony's eBook store ( now has a button on the front page that leads to the books from Google, which people can transfer to their PRS-505 or PRS-700 Reader at no cost.

"We have focused our efforts on offering an open platform and making it easy to find as much content as possible - from our store or others - whether that content is purchased, borrowed or free", said Steve Haber, president of the digital reading business division at Sony.

"Working with Google, we can offer book lovers another avenue for free books while still providing a seamless experience from our store".

The books from Google are described as "classics", older titles that are now in the public domain and no longer copyright protected.

Amazon currently offers around 250,000 titles for its Kindle ebook reader, a strong competitor to Sony's Reader series.