BT Vision is making three films available for download free of charge, provided that the viewer is prepared to watch advertisements.

Mischief Night, Played and The Punk Rock Movie can be downloaded and viewed in Windows Media Player using a codec developed by Hiro Media.

The player will show adverts from The RAC, Norwich Union and Territorial Army, among others, during breaks in the films.

Antony Carbonari, interactive and commercial media director at BT Vision, said: "We believe that sympathetically placed targeted advertising, combined with a viral film-sharing capability, will be attractive to customers in conjunction with free or reduced prices."

The viewer also has to give some demographic information which the player uses to personalise the advertising.

The computer being used to watch the films checks the data against an online database and downloads new adverts that could be more suitable.

Films can be sent to friends who must provide the same information. The films can be viewed for one month, and the scheme will last for the next three months.

"BT is taking an industry-leading stride as the first European broadcaster to allow users to download free movies, supported by demographically targeted and personalised ads, that can be shared around the internet," said Ariel Napchi, chief executive at Hiro Media.

"The great unfulfilled vision of the internet is to leverage its distribution power and word-of-mouth capabilities to provide entertainment fans with free and legal downloads that can be watched when and where they want."

The films can be downloaded from the BT Vision Download Store.