Apple hasn't yet responded to a European Commission enquiry into territorial pricing practices through iTunes music sales in Europe - but the deadline for its response has been extended.

A spokesman for competition commissioner Neelie Kroes confirmed that the deadline for a response has now been extended until 20 June. The original deadline expired at midnight on Monday night.

The investigation concerns the way iTunes sells tracks at different prices in EU states, and forbids residents of one EU country from buying their music at a better price from another state's iTunes Store.

"Customers are unable to shop around and buy from the iTunes store they would like to," said the Commission spokesman. "They are unable to buy the same tune for the same price."

The practice contravenes some basic principles of the European free market, but historically is led by the established music industry model for territorial pricing in different markets.

The Commission sent a 'Statement of objections' to Apple and the labels in April this year. It can fine companies that offend against free market rules up to 10 per cent of their annnual worldwide turnover.