The chart will be compiled by the Official UK Chart Company and is set to be broadcast on Radio 1. It will include sales data from legitimate download retailers such as iTunes, HMV, Mycokemusic.com and MSN.
The first unofficial chart has been topped by The Pixies, who have released their first new song for 13 years, 'Bam Thwock', exclusively only on iTunes.
The British Phonographic Industry said that the first official chart would appear on September 1.
Peter Jamieson, chairman of BPI, said: "There has been an incredible excitement over the past few weeks about the launch of new download services. With their choice and convenience, these services are transforming people's music buying experience."
He said that downloads were not replacing the physical single or album, but that they were generating a new way of listening to music.
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