Bestselling author Stephen King added his imprimatur to Amazon's latest attempt to break open the electronic book market today with the unveiling of a new version of its Kindle reader in New York.

The new gadget – which is due to go on sale in America at the end of February – is the second version of the Kindle, boasting longer battery life over its predecessor, as well as a storage capacity that has been extended from 185MB to 2GB.

The cost will stay the same, at $359 (£240), but the main change is in the product's design – the new Kindle sports a sleek new look that is intended to appeal more to the general public rather than the previous blocky version did.

The announcement, which was widely expected, came at an event in New York hosted by Amazon chief executive Jeff Bezos. He said that the Kindle had helped revolutionised the electronic book market since launching in 2007.

"We've been selling e-books for years, and guess what?" he asked. "It didn't work - until 14 months ago."

King, who has published more than 40 novels since 1974, read an excerpt from his new novella, Ur – which is being released exclusively for the Kindle.

Although Amazon has not revealed how many Kindles it has sold since launching the first version in November 2007, it has struggled to keep up with demand.

Citigroup analyst Mark Mahaney estimated recently that Kindle sales for 2008 could be as high as 500,000 units, putting it on a par with the early days of Apple's iPod music player and potentially creating a market worth $1bn in sales by 2010.

There is no sign that the device will be available in the UK, however. Although the device itself works outside of the US, the Kindle's Whispernet service – which piggybacks on mobile phone networks and allows it to be updated over the air – is not compatible with European telecoms systems.

Amazon has failed to reach an agreement with the continent's plethora of mobile phone companies, and has yet to announce availability outside the US.

The widely-leaked announcements also left industry observers unimpressed.

Jeffrey Lindsay, an analyst with Bernstein Research, said that was still too expensive for mainstream consumers.

"Really we don't see them as having taken the device to the next level," he told Reuters. "We think it's an incremental step of improvements. They're advancing very conservatively."