In the States, has gone a step further in rivaling Apple's iTunes offering with the news that the company is now offering rentals of films and TV shows in high definition from Amazon Video On Demand.

Customers can select from more than 500 HD TV shows and movies from Warner Bros, Sony Pictures, Paramount Pictures, Metro-Goldwyn-Mayer, Universal and Showtime Networks.

Amazon users can purchase and watch HD TV shows online on Macs or PCs, through compatible devices, or download them to their PC for offline viewing for $2.99. As a comparison, iTunes charges $4.99 for an HD rental.

In addition, the service is available through compatible including the Roku digital video player, TiVo Series3, HD, and HD XL DVRs, through the Sony Bravia Internet Video Link and on Panasonic Viera Cast-enabled HDTVs.

Using these devices, customers can now rent HD movies for between $3.99 and $4.99.