Per Sundin, managing director of Universal Music Sweden, told The Swedish Wire: "In five months from the launch, Spotify became our largest digital source of income and so passed by iTunes.
Spotify does not disclose its arrangements with royalty collectors, however it has been reported that major music labels, as well as the major independent labels, have equity in Spotify.
If true, labels are not just making money from royalties each time a track is streamed but would be in line for a share of profit from Spotify's premium subscriptions and advertising income.
In the UK, the largest digital income record labels receive still comes from the sale of tracks and albums via iTunes.
However, industry sources predict that Spotify will generate significant revenue for UK record labels within the next six months if the site continues to grow at its current rate.
A Spotify spokesman told the Daily Telegraph: "Collectively we won't be able to change the music industry model overnight -- we're seeing revenues grow month-on-month which are being shared with rights holders in line with our agreements."
However the spokesman said that Spotify expected to take "up to two years" to grow to a sufficient size in order to become a "material revenue generator for artists".