NEW YORK, USA: News Corp's MySpace, the world's largest social networking site, said on Sunday its long-expected MySpace Music joint venture with three major music labels will launch with four major sponsors underwriting the costs of streaming free music to millions of MySpace users.

MySpace said McDonald's, Sony Pictures, Toyota and State Farm will power access to be to a range of new music services by sponsoring a mix of free downloads, song playlists, and personal music players.

"With MySpace Music integration, premium brands are offering our users and their customers new ways to discover, experience, and share music online and offline, said Jeff Berman, president of sales and marketing at MySpace."

MySpace first announced in April it would be forming a joint venture with Sony BMG Music Entertainment, Universal Music Group and Warner Music Group.

The partners said the new venture would offer a range of streaming, downloads, videos, ticketing, merchandising and much else as it aimed to be a the ultimate one-stop for music fans.

At the time the MySpace Chief Executive Chris De Wolfe said the company was seeking a chief executive or president of MySpace Music to report to himself and the music labels.

But its start has so far been mired in uncertainty as it has failed to name a chief executive in time for the launch and has declined to confirm a launch date for the service, though it is now widely expected to launch later this week.

MySpace, which recently overtook Yahoo in numbers of display ads views according to comScore, sees music as an important part of its strategy to attract millions of users and to increase the amount of time they spend on the site -- thereby driving ad revenues.

While music has also been a strong feature on MySpace since it started with artist pages, most of the music has tended to be promotional in nature rather than offering opportunities for users to buy songs.

The music labels are keen for another major player to boost sales by driving competition to Apple Inc's iTunes digital music store, which is currently the No.1 music retailer in the U.S. and a leading retailer in several other countries.

MySpace Music is expected to launch with a song download service provided by Amazon.com but few other details of the new venture's attempt to be a comprehensive player have emerged.