Rocker Bono has teamed up with the Spice Girls to record a new song - to help boost their appeal and widen their fanbase. The Wannabe pop stars are due to release a greatest hits album before Christmas (07), but record label bosses fear the 1990s group will not attract as many fans as they used to - and have called in the U2 singer to help them out. A source tells British tabloid the Daily Mirror, "It might seem unusual with the Spice Girls' pop roots and the much more rockier work of Bono, but it works. "There's been a bit of unease as to how the album will perform and if there's still a solid Spice Girls' fanbase out there. "However, Bono's involvement has lifted the whole camp and he's delighted to have been asked and add his experience... Expect the unexpected." Spice Girls Geri Halliwell, Melanie Brown, Melanie Chisholm, Emma Bunton and Victoria Beckham split in 2000, but have since reformed for a 'farewell' tour, which is due to kick off in December (07).