This includes 30% of the television shows which Apple sells through iTunes.

NBC's current deal with Apple was due to end in December, but Apple said it would not sell new series of programmes as this would mean it had to end them mid-series.

Piracy talks

"We are disappointed to see NBC leave iTunes because we would not agree to their dramatic price increase," said iTunes Vice-President Eddy Cue.

"We hope they will change their minds and offer their TV shows to the tens of millions of iTunes customers."

Observers say NBC's decision was the latest effort by a media firm to seek more control from Apple over the pricing of its output.

Last month Universal Music Group was reported to be not renewing its annual contract to sell its music through iTunes - opting to have monthly deals instead.

That would allow Universal to remove songs by some or all of its artists quickly if there are disagreements on terms and pricing in the future.

NBC has been in separate talks with Apple to impose stronger piracy protection on its downloads.

Among its aims are to stop pirated material from being uploaded to iPods.