Amazon is offering e-book readers a trimmed down version of the Kindle, which it said is smaller and lighter than a paperback book.
The new-look Kindle is 21 per cent smaller than the current model, and 15 per cent lighter at only 247g. It also offers viewing improvements, with 50 per cent better contrast and 20 per cent faster page turns, Amazon said.
Added to these are longer battery life of one month - though only if the wireless is off, increased storage for up to 3,500 books, and free 3G and Wi-Fi connections.
Amazon has also launched a low-cost Wi-Fi-only model, which is pitched at consumers who want to read books on the go but are not concerned about being able to connect to 3G networks. The device offers the same standard features as the 3G version, but weighs a shade less at 241g.
While the UK Kindle with 3G connectivity costs £149, the Wi-Fi-only model costs just £109. Amazon said that this model is suited to users "who don't need the convenience of free 3G wireless".
Announcing the new e-readers, Amazon chief executive Jeff Bezos said: " Readers are going to do a double take when they see Kindle's bright new screen and feel how remarkably light the smaller 8.7oz design feels in one hand.
"If you don't need the convenience of 3G wireless, we have an incredible new price point of £109 for Kindle Wi-Fi. It has all the same features, same bookstore, same high-contrast electronic paper display, and it's even a tiny bit lighter."
Both models include screens improved against previous models. For example, the high contrast electronic ink should make it easier to view text in bright sunlight, while in general this has improved the sharpness of text and images.
Amazon will launch a UK version of its bookstore in time for the late August release of the devices.
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