Digital music sales have doubled in the last year - but music industry sales continue to decline, new research reveals.

The International Federation of the Phonographic Industry (IFPI) this week confirmed that digital music sales continue to grow fast, but the growth hasn't kept pace with declining CD sales.

Sales of downloads via computers and mobile phones were up 85 per cent to $2.1bn in 2006. They accounted for 11 per cent of global sales - they accounted for just 2 per cent of sales in 2004.

Apple accounts for an estimated 70 per cent of the online music download to own market, meaning it now effectively controls the only growing music industry business segment.

IFPI chairman John Kennedy said he had hoped the CD sales decline would have been offset by digital sale increases: "While digital sales have grown as expected, physical sales have fallen by more than expected," he said.

But the total value of global music sales continued in its seventh consecutive year of decline. Total sales were $19.6 billion in 2006, down 5 per cent from $20.7 billion i 2005.

While the industry continues to decline, Kennedy believes digital music sales could climb by a further 50 per cent this year.