Madonna releases track online

Madonna has released her new song 'Hey Yoy' online - and the first million downloads are free.

The Material Girl - who is headlining the London leg of this summer's Live Earth series of concerts - has teamed up with hip-hop star Pharrell Williams for the ballad, in a bid to raise awareness about the effects of climate change.

But the duet doesn't specifically talk about global warming - instead the lyrics refer to loving and saving each other.

The track is available on MSN.com, and Microsoft have pledged to donate 25% of each download to the Alliance for Climate Protection.