Vivendi's Universal Music Group, the world's largest music label, said it will test the sale of songs from artists such as Amy Winehouse, 50 Cent and the Black Eyed Peas, without customary copy-protection technology.

The company said in a statement it will allow the sale of thousands of its albums and tracks available in MP3-form without copy-protection software, known as digital rights management, over a trial period. Universal's test-run marks a departure from the music industry's common practice, with most major recording studios insisting that music sellers use DRM technology to curb online piracy.

"The experiment will run from this month to January and analyse such factors as consumer demand, price sensitivity and piracy in regards to the availability of open MP3s," Universal said.

Vendors including Google, Wal-Mart, and Amazon.com Inc., will participate in the DRM-free trial, Universal said.

But missing from the list of participants is Apple Inc.'s iTunes online music store, the third largest music retailer in the US.

Songs purchased through the programme can be played on a range of MP3 players, including Apple's popular iPod, Universal said.