Millions of television viewers are now using file-sharing services to access free and unauthorised copies of programmes, research has revealed.

US drama Heroes was the most popular illegal download this year, according to research firm Big Champagne.

About 55 million people downloaded the show, while 51 million chose to access Lost, the second most popular show.

Visits to leading "torrent" sites, which index video and music files, have also nearly doubled in the last year.

The proportion of file-sharing involving films and television rather than music is continuing to rise, the research shows.

"Millions of television viewers now access free, unauthorised versions of favourite shows at least some of the time," says Eric Garland, chief executive of Big Champagne.

"This is a socially acceptable form of casual piracy - and it is replacing viewing hours."

Full story: BBC News