Hollywood has finally entrusted its blockbusters to the web with six major studios joining forces for the first time to make new films available to download over the internet on the same day they are released on DVD.

More than 200 titles will today go on sale through Movielink, a film site set up in 2002 as a joint venture between Warner Brothers, Sony Pictures, Universal, MGM and Paramount.

The site will offer films from its owners and from 20th Century Fox, the studio that is owned by News Corporation, the parent company of Times Online.

In what the studios hope will prove a major draw, forthcoming attractions available to buy on the site will include cinema hits such as Harry Potter and the Goblet of Fire and King Kong.

Movielink's backers have argued that film downloads have so far failed to catch on because must-watch titles have only been available to buy online as long as two months after they hit supermarket shelves as DVDs.

A second site, CinemaNow, is to sell downloadable versions of more than 85 films from Sony, MGM and Lions Gate, the independent studio behind Crash, this year’s winner of the Oscar for best film. Lions Gate also holds a stake in the company.

Curt Marvis, the chief executive of CinemaNow, said: "This is the milestone we've been waiting for. CinemaNow has always believed that the ability to sell studio movies at the same time they are released for home video would be the catalyst for explosive growth in our industry.

"Now our customers can download and own the movies they want, when they want, with the convenience of on-demand access."

The two sites have so far only released pricing details for the United States, where films will be sold for between $30 (£17) for new releases and $10 (£6) for older titles. Until now, both services offered "rental" downloads, which expired after a limited time.

The film industry is expected to turn its attention to the British market where consumers have already warmed to online media. Yesterday, the pop track Crazy, by Gnarls Barkley, became the first song to reach No1 in the UK’s music singles chart solely through internet downloads.

Movielink and CinemaNow will aim to emulate the success of iTunes, Apple's online music store, which has sold more than 1 billion tracks. In what could be a boost for Microsoft, a fierce rival of Apple, Movielink will use its Windows Media format.

However, question marks have been raised over whether the new film services offer good value for money. In America, some films which are being offered on CinemaNow and Movielink are cheaper to buy as DVDs in stores such as WalMart, which sell them as loss-leaders.

Moreover, some critics have pointed out that the downloadable versions do not come with features such as extra scenes that DVD buyers have come to expect and that some users could find the internet formats unwieldy.

CinemaNow will allow the movies to be played only on one computer. Movielink will allow the movie to be copied onto a DVD, from which the movie can be downloaded to two other computers, but it cannot be played on a conventional DVD player.

An average film will require around 1 gigabyte of hard-drive space and will take up to about two hours to download over a high-speed broadband internet connection.

It will also be tricky for many potential customers to watch the downloaded films on their television sets – although several devices, including the Viiv PC from Intel, which will store digital films and allow TVs to be connected to the web, are expected to be released later this year.

But today’s move still marks a major departure for the film industry, which had proved reluctant to make its most valuable titles available on the net.

Until now, the film industry had seemingly sought to protect DVD sales, even though online distribution offers the prospect of stripping out traditional distribution costs and inventories.

Studio executives were also mindful of the setbacks experienced by the music industry, which claims to have lost millions in revenues from online pirates.

Hollywood has already been hit by bootlegged blockbusters. Last year, a pirate copy of the final part of the massively lucrative Star Wars franchise, Revenge of the Sith, was made available online within hours of the film’s cinema release.

The technology used to share bootlegged material has been dubbed the "darknet" by Microsoft engineers in a paper posted on www.bearcave.com. Despite vast funds spent on countering piracy it would inevitably "become more widespread", they said.

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