British media group BSkyB will next week launch Sky Songs, a digital music service it hopes will challenge Apple's iTunes and Spotify in the music downloads business.

BSkyB said on Sunday the service, which will go live on October 19, would offer access to over four million tracks for download and ad-free streaming.

It will include new releases and back catalogues from all four major music labels -- EMI, owned by private equity firm Terra Firma Capital Partners, Sony, Universal and Warner -- plus a range of independent labels and distributors.

The service will be operate on a subscription basis in contrast to the track-by-track purchasing model of iTunes.

There will be no advertiser-funded element such as that used by Spotify, which provides free access to music, but plays advertisements too.