The DX has a screen with 2.5 times the surface area of the original Kindle, supposedly making it ideal for newspaper and magazine readers, although UK subscribers will be disappointed to find that downloads do not contain pictures.

The release came as Amazon announced on Christmas Day that it sold more electronic books than it did traditional paper books for the first time.

The success of electronic sales over Christmas should be taken with a pinch of salt when contemplating the implications it will have on the future of paper books, as with Amazon not releasing any official sales figures, it is believed that the statistics only refer to Christmas Day – a day when the majority of people buying books are doing so to test out their new Kindles.

David Taylor, president of on-demand book printer Lightning Source, said that he did not see the e-book as a major threat to publishers, with many involved in the distribution of e-books, as well as the more traditional paper books.

Taylor commented that many printers and publishers, including Lightning Source, are viewing the e-book as "a way of giving the consumer more choice".

He claimed that the two forms of books "are complementary", with many books being sold in both forms, with discounts on the e-book when you purchase the paper version. Publishers, he added, are using e-books as a promotional tool and as a means to test new authors.