RealNetworks is planning to join the rush for the emerging market in online music.

The company intends to launch Rhapsody, a subscription service, in Europe next year. It is currently available to customers in the US who pay $9.95 (£5.90) a month plus 79 cents for every song downloaded.

A growing number of media, retail and technology groups are rushing into the nascent market which delivers music legally over the internet.

The illegal online piracy of music has been blamed by the music industry for devastating conventional sales. Global music sales fell by 11% in the first half of the year, but the early evidence suggests there is an appetite for legally downloading music.

The biggest player in the advanced US market has been Apple Computer, with its iTunes service. Since the service was launched in April, users have downloaded 14m songs at 99 cents a time.

A Windows version of iTunes was launched last Thursday and has already sold more than 1m songs, Apple said. It has not yet set a date for entering the European market.

Rhapsody carries a catalogue of 385,000 songs for web streaming and more than 275,000 for permanent download.

The Seattle company, better know for its video streaming software, said that 21m songs had been streamed on the US service during September.

Microsoft launched a pay-as-you-go service in Europe last month. Users can download any of 200,000 songs from 8,500 artists. Next spring, Sony intends to offer a service in the US and Europe which will use a similar device to Apple's iPod.

Others looking at the possibility of launching services include Time Warner and MTV, the cable television music channel. Roxio, a Silicon Valley software firm, has rebooted Napster, once the most notorious peer-to-peer service, as a fee-paying business.