Google turned the music business into a battleground yesterday with its entry into the arena , competing head-on with iTunes and Amazon .

The new Google Music download store on the Android Market is a cloud-based service . Users will be able to store all their songs and access them on any PC or Android-based mobile device.

Google has done deals with three of the world's four biggest music companies -- Sony, Universal and EMI - although some people worry about users being able to upload illegally downloaded music to the Google service.

Google+ users who purchase songs from Google Music can offer a limited number of free "listens" to the song to their contacts on the social network, reported the San Jose Mercury News.

Apple has long been No 1 in digital music downloads, though Amazon is running hard and also offers a cloud-based storage service.

Apple this week launched iTunes Match, which lets users upload songs not purchased through iTunes onto cloud servers that can be accessed on PCs and iOS mobile devices.

However, that service costs $25 a year; Google Music's service is free.