An in-house video advertisement for an all-you-can-read service was circulated on a Kindle forum this week promising reader access to popular titles such as the Man Booker prize winner The Life of Pi, Sara Gruen's Water for Elephants and the Hunger Games, Harry Potter and Lord of the Rings, ''all in the palm of your hand''.

The Kindle Unlimited program appears to offer unlimited access to more than 600,000 backlist and self-published titles as well as thousands of audio books for $US9.99 ($10.65) a month – although there is no absolute certainty Amazon will go ahead with the scheme.

Amazon's testing of the new subscription model follows the entry of new digital player Oyster, referred to as the Netflix of books. Oyster offers unlimited access to more than 500,000 books for $US9.95 a month. Readers of competitor Scribd can read unlimited books for $US8.99 a month.

Kindle Unlimited was yet another attempt by Amazon to send a wrecking ball through its competition, said Joel Becker, chief executive of the Australian Booksellers Association.

''I think the industry – authors, publishers and creators – are finally waking up to what booksellers have already known: that Amazon’s business practice create a mammoth problem for an essential cultural industry,'' he said.

'''They don’t pay their fair share of taxes, they avoid paying GST, they sell significant portions of their product at or below cost and at a loss. One day their shareholders will wake up to their practices.''

Booktopia chief executive Tony Nash said it was unsurprising that Amazon would move towards a subscription business model, given its competition.

Mr Nash said the attractiveness of the deal for readers would rest on the strength of titles carried by the Kindle library – namely, if it included new releases, the backlist of internationally popular authors or New York Times bestsellers. The popularity of Android tablets mitigated against the Kindle library.

''I think if all publishers and authors are included in the same pool, not one is going to make money, not even Amazon. Authors won't make enough and publishers won't make enough,'' he said.

Books were not as portable as music, which can be played virtually any place, anywhere, Mr Nash said, and even the most voracious readers of romance might wonder if a digital library could offer fair value.

Sydney bookseller Jon Page said he had a lot of concerns over e-book subscription models and he worried for the viability of the book industry.

Digital libraries utilise an author's backlist, the long tail of which sustains many publishers, authors and bookshops.

''I am also concerned about author royalties,'' Mr Page said. ''Authors are already getting a smaller cut when it comes to e-books and when you look at the music subscription services, it is the music companies who are making money and the artists who are getting less.

''I am very surprised that publishers who have resisted library e-book lending for years are now embracing subscription services.

''The fact that Amazon is going to enter the subscription market with their already anti-competitive Kindle device has me very worried for the viability and sustainability of the book industry as a whole.''

Amazon Prime already offers a premium membership for a range of privileges, including a lending service.

At the start, in November 2011, author Nick Earls said the pool for content providers like himself was something like $500,000 a month and book borrowings were at a level that led to payments of about $1.50 a borrowing.

Were it ever to get to the point where, like musicians signed to Spotify, authors were to be paid in fractions of a cent, it would be a ''nightmarish figure''.

''A book is different from a song – a novel is a 10-hour proposition rather than three minutes, and it can’t operate in the background and is unlikely to be reread as many times as a song is listened to – and pricing needs to reflect that,'' he said.

Amazon has not yet responded to questions put to it by Fairfax Media.