The explosion in online music sales is set to continue and will start to halt the decline in overall sales of recorded music in Europe, but not until 2010, according to a report on Thursday.

Within four years, European spending on online music will rise to more than 1.1 billion euros ($1.4 billion) from just 121 million euros in 2005, media researchers Screen Digest said.

Online music has been booming. However, online sales alone are not going to be enough to halt the decline in music sales, said Screen Digest's Dan Cryan.

The music industry needs to make the most of new delivery platforms. We believe that with the right strategy - including mobile and online - the worst might be over by 2010, the author of Online Music in Europe: Market Assessment and Forecast said in a statement.

The overall European music market has lost 22 percent of its value since 2001 due to a combination of factors, including piracy and the shift by retailers toward DVDs, books and mobile phones at the expense of CDs.

Screen Digest said it was likely the growth in DVD sales was partly responsible for the drop in physical music sales.

But, while illegal downloads continue to be a problem, the situation is improving.

Data from the music industry body, the International Federation of the Phonograhic Industry (IFPI), indicate online piracy is declining - the number of tracks available on illegal file sharing networks fell to 885 million last year from 1.1 billion in 2003.

A survey by market research group Forrester in March forecast that online music sales will grow rapidly over the next five years, although traditional music sales will still make up almost two thirds of revenues in 2011.