Internet search giant Google has officially unveiled its much-anticipated music service called Google Music.

A rival to the likes of Apple's iTunes, Google Music allows users to discover, buy and share music with their friends on the company's social networking platform Google+.

Google Music offers millions of songs from acclaimed record labels Universal, EMI and Sony Music. However music from forth major record label Warner Group will not be available on the new service.

US consumers will be able to buy music via Google's Android Market, which already offers smartphone applications, electronic books as well as videos.

Describing the benefit of the new service for self-released artists, Google's Jamie Rosenberg said, "For self-released artists, the Google music artists' hub offers the same access to Google music as the superstar many of them hope to become. No other major music retailer offers this kind of direct access."

The new service, which was introduced at an event in Hollywood, California, is allowing US customers to download one song for free every day.

Songs have been priced at free, 69 cents, 99 cents and $1.29 apiece.