Advertisement, which makes the Kindle electronic book reader, said Monday it added a new video feature to the software that lets people read Kindle books on Apple gadgets.

Amazon makes free Kindle e-book reader applications, or "apps," so people can buy and read its e-books on devices other than the physical Kindle, such as an iPad, iPhone or iPod Touch from Apple Inc. Owners of those gadgets can download the Kindle software without charge from Apple's iTunes App Store.

The newest version of the app can now play video and audio clips embedded in e-books.

It's a move that could help Inc. continue to compete with Apple, a new but formidable competitor in the electronic book market.

Apple launched the iPad, a tablet-style computer with a built-in e-book reader and online e-book store, in April. The two devices use very different technologies, each with benefits. The iPad's color screen makes for better rendering of illustrations and photos in books, and the touch-sensitive screen lets people drag a finger to simulate the turn of a page. The Kindle is grayscale and requires users to press a button to flip pages, but its electronic-ink screen can be read in bright sunlight while the iPad succumbs to glare.

The company said one of the books that takes advantage of the new technology is the travel guide "Rick Steves' London," which includes embedded walking tours people can listen to while exploring the city.

Amazon also said Monday that the iPhone Kindle app has also been optimized for the new higher-resolution screen on Apple's iPhone 4.