Spotify and other streaming services are reportedly being pressured to encourage free users to move onto a paid subscription.

As Digital spy reports citing Financial Times, Universal Music is using licence negotiations with Spotify as an opportunity to change the way its 'freemium' model works.

The music giant is apparently concerned that the availability of free music on streaming platforms is harming sales of paid-for music in stores and via download.

Universal Music CEO Lucian Grainge has already publicly questioned the model's future, saying: "Ad-funded on-demand is not going to sustain the entire ecosystem of the creators as well as the investors."

At present, free users are able to listen to ad-supported music on Spotify for an unlimited period of time, although they can only listen to curated playlists on mobile and cannot make tracks available offline.

It's not clear how music labels want to encourage free users to upgrade to a paid subscription - a cap on the amount of time spent on the service could be one solution under consideration.

However, Spotify fears that restricting free users could push them towards illegal downloads or listening freely on YouTube.

"Without free, pay has never succeeded," Jonathan Foster, head of Spotify's Nordics region said. "We're one of the greenest shoots of growth in the industry. We don't want to destabilise that. We think that this model works."

Last year, Taylor Swift famously removed all of her music from Spotify.