CD sales continue to decline as music downloads continue to grow in popularity, new figures reveal.

According to the British Phonographic Industry (BPI), just short of three million tracks were purchased online during the final week of 2007.

The figure, 2.94 million, is an increase of 100.2 per cent on the 1.47 million tracks purchased during the same period in 2006.

The BPI, whose figures came from the The Official UK Charts Company, also revealed a 50 per cent increase in music download sales on 2006, topping 77 million, whereas CD sales dropped during the same period.

This trend is repeating itself in the US, with music CD sales down 15 per cent last year as consumers turned to legal and illegal digital downloads, according to research.

Sales of physical CD albums dropped to 500.5m in 2007, a three-fold increase on the 4.9 per cent fall suffered in 2006, according to Nielsen Soundscan, an information system that tracks sales data for singles, albums and music video products for music companies in Canada and the United States.

Downloads for independent labels are also rocketing and according to download subscription service Emusic, these sales also smashed retail expectations during the 2007 Christmas period. On Christmas Day alone indie labels clocked up almost half a million downloads of music and audio-books.

Matt Phillips, BPI director of communications, said: "Recent years have seen a boost in download sales in the week after Christmas, but this was a larger increase than expected, and sales should continue to grow throughout 2008.

"The enormous choice of music and great value for money, combined with the ease and convenience of downloading, means legal digital music services are becoming increasingly popular with music fans."