Instead of "Think Different", perhaps Apple's slogan should be "Price Different", says a group of disgruntled UK music fans.

The Consumers’ Association is calling for an investigation into Apple's practice of charging different prices in different European countries to download songs from its ITunes music store. The consumer group says this practice is unfair and may breach European regulations.

UK residents pay £0.79 to download a song from iTunes. In France and Germany the price is €0.99 (around £0.66), meaning UK customers pay about 20 percent more than their counterparts abroad, a Consumers' Association statement said.

The consumer group wrote to the Office of Fair Trading (OFT) this week, seeking an investigation into what it calls a potential breech of competition law. UK consumers are entitled to equal prices under Europe's single market regulations, says John Cox, a spokespeson for the group.

Apple representatives in the UK decline to comment, referencing only a statement the company issued in June when iTunes launched in Europe.

"The underlying economic model in each country has an impact on how we price our track downloads," Apple said at the time. "That's not unusual, look at the price of CDs in the US versus the UK. We believe the real comparison to be made is with the price of other track downloads in the UK."

The Consumers' Association was dissatisfied with the explanation and wants the OFT to take a closer look, Cox says. The association stopped short of filing a "super complaint", he notes, which is reserved for the most egregious cases and would require an OFT response within 90 days.

US consumers pay $0.99 for each iTunes song. Rival RealNetworks charges $0.49 per song through its Rhapsody service.

The iTunes service requires customers to provide an address and a means of payment, making it difficult for UK customers to use the French and German services and pay the lower prices, the consumer group says.

Cox declines to say whether the group believes all online retailers, such as, should be required to charge the same price for a product in all European countries.