Apple is now selling some 2.7 million tunes per week

The number is short of its 100-million target, but it still well ahead of rival music services.

Apple boss Steve Jobs said he was not at all disappointed with the figures, saying iTunes had "exceeded our wildest expectation during its first year".

The iTunes store has had a big impact on the music industry, proving there is a market for paid-for downloads.

iTunes update

Apple entered the world of music downloads last April, offering songs from a catalogue of 200,000 tracks for 99 cents (60 pence).

It is now selling about 2.7 million songs per week and the number of tracks on offer has risen to more than 700,000.

Apple has upgraded its iTunes music software

Apple expects this to rise to more than a million by the end of the year.

"We're very, very excited about the results from the first year," said Mr Jobs.

"If a year ago anyone had predicted iTunes would have sold 70 million songs, they would have been laughed out of town."

To kick-off its second year, Apple is offering a free song a day to customers for the next eight days.

The California computer maker has also released a new version of its iTunes digital jukebox software.

Among the additional features are the automatic conversion of songs in Microsoft's Windows media format, WMA, to Apple's AAC format.

At the moment, the iTunes store is only available in the US. International versions of the online store are expected to be launched later this year.

In Europe, rival Napster is racing to launch ahead of Apple, while in the UK, MyCokeMusic and services such as HMV and Virgin are beginning to get a foothold in the market.