U2's Super Bowl exclusive a big hit

U2's Super Bowl exclusive has paid off - the group has raised over $3 million for the Global Fund to fight AIDS, malaria and tuberculosis from downloads of their new tune.

The Irish group premiered a snippet of its new single, Invisible, during the big game, in partnership with frontman Bono's (RED) charity - and fans have flocked to iTunes to download the free track.

More than one million free downloads were snapped up within the first hour after the commercial aired during the first quarter of the Super Bowl telecast, and the success of the campaign has prompted bosses at sponsors Bank of America to exceed their initial pledge of $2 million during the 36-hour giveaway.

All proceeds from additional copies of Invisible, which is now on sale through iTunes, will be donated to the Global Fund as well.