Apple and the 'big four' record labels - EMi, Warner Music Group, Universal Music Group and Sony BMG - are set to appear before an EU anti-trust commission this month as part of a probe into iTunes pricing.

The four big labels are accused of pressuring Apple into country-specific pricing - something that's against EU anti-trust laws. This is why iTunes demands that you have a valid credit card for the country where you'd like to buy songs. It may also explain why there is such wide price variation across the EU.

Apple and the record labels are set to appear on Wednesday 19 September and Thursday 20 September. However it's unlikely that the EU will take any action immediately, Ars Technica says.