Amazon, the online store, has extended its e-book service in the United States to offer e-books that can be read on Apple's iPhone or iPod touch.

Amazon has produced a free "app", or program, which will bring many of the functions of its Kindle e-book reader to the smaller screen of the iPhone and iPod Touch.

The online retailer is hoping that the app will help broaden the e-book market, which Amazon itself ignited with its electronic book reader, Kindle. Fans of e-books will be delighted that they are now available for the Apple machines, since a Kindle costs $350, $120 more than the cheapest iPod touch. Neither the Kindle nor the new application is yet available in Europe.

The app, available as a free download from Apple's app store, allows iPhone and iPod Touch users to read the same electronic books that Kindle owners can buy on Amazon.com. As with the Kindle, the iPhone app lets users change the text size on the screen, and add bookmarks, notes and highlights. Although other e-book readers are available as apps on Apple’s products, this is the first time that Kindle e-books have been made available through the App Store.

The application does not connect to the Kindle store, however, so users must access the web browser on their iPhone, iPod or computer to make a purchase. If someone happens to have a Kindle and an iPhone, Amazon's program will be able to synchronise the two so you can keep your place in the same e-book on both devices.

Amazon unveiled the latest version of the Kindle on February 9. The Kindle 2 costs the same as the original electronic reader, but is thinner and has improved battery life and storage capacity.

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