The row over royalties from downloaded music escalated on Friday when the UK’s composers and songwriters took legal action against record companies, challenging them to disclose their revenues from the sale of music sales over the internet.

The move comes as talks have broken down this week between the two sides to try and resolve a bitter dispute over how much copyright holders should receive from music downloads. Music sales over the internet currently account for about 10 per cent in the UK, but is growing rapidly, and music executives expect a quarter of all sales to come from downloads in the next few years.