Apple sold ten times as many tracks in the US as its most established future rival in Europe, OD2, sold in 2003.

The Mac-maker shifted 30 million songs in the US, while OD2 has shifted just three million songs in Windows Media format across the multiple operators that use its service in Europe last year.

Speaking to Reuters, OD2 CEO Charlie Grimsdale, who co-founded the company with Apple master Peter Gabriel stressed the future importance of online music sales: "I have to believe electronic distribution of music will be an increasingly important part of the business for record labels."

He added that the volume of European music downloads is growing 25 per cent month-on-month.

Apple is expected to launch its own music download service in Europe in the second quarter.