By Darren Waters
BBC News Online entertainment staff
Apple's pioneering online music service iTunes music store is expected to launch in the UK next week.
Napster has been available in the UK for more than two weeks
The service will offer UK iPod owners the chance to buy music from the site for their devices for the first time.
It has proved enormously popular in the US, with more than 70 million songs downloaded by users in its first year.
ITunes is due to be unveiled in London on 15 June, according to sources. Apple's rival Napster launched a legal download service in the UK on 20 May.
The two companies are expected to battle it out for a slice of the increasingly lucrative legal download music market.
On Monday, Napster announced it has increased the size of its music library in the UK by 40% to 700,000 songs.
Apple's iTunes is now available for users of Windows XP and 2000
Although the market is still in its infancy, more than 500,000 music tracks have been downloaded legally in the UK so far this year.
Apple has called a press conference for 15 June, saying "the biggest story in music is about to get even bigger".
Based on past launches, the service would be expected to go live immediately.
But the company would face far stiffer competition in Europe than it does in the US.
In addition to Napster, Apple would have to compete with OD2, which provides downloadable songs for companies such as Virgin, HMV and Coca-Cola and is currently the UK's most popular online music store.
And Sony plans to launch its Connect music store in the UK, Germany and France at the end of June.
The iPod is the only portable music player available that plays songs from the iTunes music store.
The major record labels are keen for industry-backed music stores to launch in Europe to stop pirated tracks being swapped over the internet.
The precise size of the Apple library is unknown, but songs are expected to cost 99p each in the UK.