Online shopping for films is yet to really catch on

It is beginning by selling digital downloads of about 3,000 films and episodes of popular television shows to customers in the US.

It hopes to use its buying power to beat off competition from rivals including Apple's iTunes store.

Wal-Mart already accounts for about 40% of US DVD sales, giving it considerable influence with film studios.

The store sells movies from most major studios, with older titles starting at $7.50 (�3.82) and new releases from between $12.88 and $19.98.

Choice

Apple has only secured deals to sell films from Walt Disney and Paramount - with most refusing to sign a deal because of Apple's desire to sell all films at the same price.

The real problem is that people want to watch these movies on their television set Josh Bernoff, Forrester Research

The Wal-Mart downloads will not work on Apple computers or iPods.

They can be viewed on a PC or transferred to digital players which are compatible with Microsoft Windows Media Player but cannot be burned to DVD.

This limited viewing ability will be a challenge to Wal-Mart, analysts say.

"The real problem is that people want to watch these movies on their television set," said Josh Bernoff of Forrester Research.

"There is already an effective way to do that which is to buy a DVD."

Amazon are among other firms already offering online movie downloads in the US.