LONDON (Bloomberg) — The UK television industry is losing revenue as millions of viewers illegally access shows such as "Heroes," "Lost," and "Gossip Girl" online, said Uk music-royalty collection agency PRS for Music.

With the number of illegal file-sharing sites growing, the industry stands to lose millions of pounds in subscription and advertising revenue, and from the sale of series and films, the agency said.

UK show "Top Gear" is one of the most commonly swapped shows, especially in the U.S., the study found. "Slumdog Millionaire" and "Twilight" rank high among pirated films.

"It is important for the film and television industries to understand and learn from the experience of the music business and to look not just at possible lost value, but the opportunities that digital distribution can bring," PRS's chief economist, Will Page, said in the statement.

Piracy has hit the music industry so hard that sales of music are now at 1994 levels, PRS said.