Apple has confirmed that over 12 million videos have been purchased and downloaded from iTunes.

CBS Corporation's Showtime Networks and Apple have also added premium cable programming from Showtime, including recent Golden Globe nominees "Sleeper Cell" and "Weeds" to the catalogue of video available on the iTunes Music Store.

The news means iTunes in the US now offers over 50 TV shows for $1.99 per episode.

"iTunes allows fans of these hit Showtime programs to purchase and watch them in an innovative way," said Matthew C. Blank, chairman of Showtime Networks. "It is also a tremendous opportunity for non-subscribers to sample Showtime's programming."

New shows include "Sleeper Cell", "Weeds" and the complete first season of "Fat Actress" starring Kirstie Alley.