According to Spotify, the format has been changed because the "huge demand" caused by the for and handsets running the platform, this week.

"We are going to have to temporarily reinstate our invite system in the UK. We are invite-only in all our other launch countries but we hope to be able to remove the need for an invite again very soon," said Spotify's Andres Sehr in a .

Spotify lets users create a playlist of songs for free, although tracks are peppered with adverts just like commercial radio.

The service also allows users to create 'collaborative' playlists, which are assigned their own web addresses, and can then be added to by other Spotify listeners.

The invite-only platform, which was , means that new users must be 'invited' to join the service by current member, or join a . However, Spotify did say that Premium members, that pay a £10 per month subscription to enjoy ad-free listening on the service, could register directly.