A war of words erupted between NBC Universal and Apple yesterday, laying bare the tension between media and technology companies as they fight for advantage in the burgeoning market to sell video online.

The two companies had been negotiating to renew NBC's contract to sell its television programmes through Apple's iTunes digital media store. But the talks soured after NBC told Apple it would not renew theoriginal deal because of frustrations about iTunes' pricing policy and anti-piracy controls. Apple accused NBC of trying to push a "dramatic price increase" on consumers, and said it would drop the network's new autumn television programmes from iTunes.