Record labels are increasingly infuriated at Apple's successful music products, Bloomberg reports.

They seem annoyed that rather than buying digital versions of music they already own, users are instead choosing to rip that music from the CDs they already own.

Recent statistics have shown a slowdown in the rate of growth in digital music sales in the US, leading some alarmist analysts to speculate that optimism around such sales may be misplaced.

While record labels grabbed huge amounts of consumer cash in the eighties when many music lovers flocked to shops to buy CD versions of the vinyl they already owned, consumers will not accept the conceit that they should be forced to buy digital versions of music they have already acquired.

IFPI head John Kennedy said: "We're still optimistic that figures for the year will show a doubling over 2004 or even a tripling," he said, warning against seeing the war and hurricane torn US as an example for the world.

The labels also continue to push for variable pricing: "There will be variable pricing, multi-tier pricing,'' said Universal Music CEO Doug Morris last month. "The issue is going to be when and who blinks first.''