The new MySpace Music service launched in the US on Friday
There will be an "exodus" of music artists from MySpace in a row over the website's new music download service, a record label boss has warned.
Independent record labels have cried foul after failing to reach a deal for their acts to appear on MySpace Music.
"MySpace has been floundering lately already, and people have been moving toward Facebook and so on," said Tom Silverman, boss of Tommy Boy Records.
MySpace said in a statement it remains "committed" to independent music acts.
"We believe that all artists will be able to enjoy the benefits longer term. In the meantime we invite and welcome discussion with artists, labels and independent representatives at any time," it added.
MySpace has joined forces with the four major record labels for their stars to appear on the service.
But many in the independent sector feel that much of MySpace's success has been built on the presence of new and indie acts.
That has led Mr Silverman, who signed De La Soul, Queen Latifah and Coolio, to comment that "our lovers were cheating on us".
"Now we need to hire a great divorce lawyer," he told the Los Angeles Times.
He added that the latest developments would "accelerate the exodus" of acts from the site.
MySpace is widely seen as the top destination for new and established artists to showcase their songs and keep in touch with fans. An estimated five million acts have MySpace pages.
The new ad-funded service, which has just launched in the US, lets MySpace members listen to streamed tracks for free or download them through partner site Amazon.com.
The four major labels have been given a stake in the new site and the independent labels want a similar deal.
They say that is not currently the case, although MySpace said it had provided everyone with the "same opportunities".
The indie labels include Beggars Group, which has Radiohead, MIA and Vampire Weekend on its roster.
Beggars chairman Martin Mills said: "We believe that independent music and artists are worth every cent as much as that of the majors, and will not be supporting this potentially exciting new service until we see fair play."
Other companies not signed up include Domino, home of the Arctic Monkeys and Franz Ferdinand, as well as rock label Epitaph, dance hothouse Warp and Koch, the largest independent label in the US.
Koch president Bob Frank said: "Our issue is not with the majors having equity, but with MySpace believing that we would accept this without similar terms.
"MySpace continually states that it is embracing the independents. It's a pretty listless and cold embrace."
Indie rights body Merlin is negotiating for its 12,000 labels, which have a 9% share of the US music market - roughly the same as the smallest major, EMI.
In a statement when the service launched, MySpace said: "We have offered Merlin a relationship that provides the same opportunities to Merlin's labels and artists that we have provided to all labels and artists."
A UK version of MySpace Music is expected to launch in early 2009.