The service is only available to Mac users in the US

An insight into the success of Apple's online music service has been provided by leaked details from a meeting with representatives from the independent record industry.

According to notes published on the web, Apple has sold 3.5 million songs since it launched its iTunes music store at the end of April

The computer manufacturer is selling about 500,000 songs a week and about half of those are sold as albums, allaying fears that people would choose individual tracks instead of a whole record.

The notes from the 5 June presentation behind closed doors by Apple boss Steve Jobs were leaked by independent record retailer CD Baby, which has since pulled the details from the web.

Bouyant sales

Apple's music store has proven to be a major commercial success, overshadowing the online subscription services offered by the major record labels.

The iTunes store has more than 200,000 songs from artists such as U2, Eminem and Sting for sale at 99 cents (62 pence) each.

The service got off to a flying start, selling a million tracks in its first week.

The initial buoyant sales have continued. The leaked notes from the meeting last week show that Apple has sold 3.5 million songs in the six weeks the store has been open.

Worries in the record industry that customers would cherry-pick hits have not come true, with 45% of all songs downloaded as part of a full album.

The store offers an opportunity to sample 30 seconds of a track before you buy. The notes say that people tend to listen to 10 previews for every song they buy.

And most people seem happy to store their credit card details on the iTunes store. Some 90% of sales are one-click downloads, which means a credit card is automatically charged when a track is bought.

Private meeting

About 150 representatives were invited to the meeting with Steve Jobs to discuss making their music available on the iTunes store.

The meeting was supposed to be private, but notes taken by one of the people at the meeting have leaked onto the net.

CD Baby took the notes off its website shortly after posting them. A note on the site says: "Sorry, there used to be more details here. I didn't realise yesterday's presentation was supposed to be confidential.

"When I found out, I pulled the details. Honest mistake."

However, the information has found its way onto other sites.