The social music discovery service mflow has officially launched in the U.K.

It was has been operating a closed trial for 10,000 invited users since October 2009. From April 15, it has removed access restrictions, though it remains for U.K residents only at present.

The mflow application allows music fans to follow other users, build a network of trusted sources, discover new music and recommend music to others, as well as purchase MP3s. When a user 'flows' a track to someone else, that second user gets to stream the track in full once.

It has agreements with the majority of independent labels including Beggars Group, Believe Digital, Domino, INgrooves, and Skint, and has just announced two new content agreements with IODA and Ministry of Sound. It also has deals with Sony Music and Universal Music and is in negotiations with EMI and Warner Music.

The service rewards users for recommending music: if a follower likes the track and goes on to buy it, the user who recommended it receives 20% of the purchase price in credits to spend on more music.

Sources said the trial showed the business model could work, as mflow was covering the streaming costs owed to rights holders from sales of tracks that had been recommended. There is no advertising on the site.

An industry launch of the service was staged at Ronnie Scott's in London last night (April 14).

"We are delighted that after six months of highly successful testing involving 10,000 invited users who have provided us with invaluable feedback and input about our service, we are now ready to remove access restrictions and let the general public use mflow," said CEO Oleg Fomenko in a statement.

"We are evolving quickly as a company and adding both content and user functionality every day so we are a little reluctant to call this a full public launch. We are, however, very proud of what we have achieved to date and are eager for people to start using the system and discover new music. Moving forward, we are confident that mflow will provide the template for social music discovery."

Media partners such as Q, NME, Mojo, Uncut, Clash, xfm and Absolute Radio are using the service, along with Zane Lowe of national top 40 station BBC Radio 1.

As previously reported, Island Records has used mflow to run an awareness campaign for new signing Lauren Pritchard and will be doing the same with Pete Lawrie. Both artists performed at the launch.