Mel B, aka Scary Spice, of the disbanded Spice Girls is the only person stopping the Spice Girls reforming, says concert organizer Sir Bob Geldof.

According to Annanova.com, the veteran rocker is desperate to reunite the fab five for his Live 8 extravaganza next month - but he says she won't say yes.

Now he will make an 11th hour call to Scary Spice in a bid to get her on board, and spark one of the biggest reunions in pop history. And he said if she still refuses, the four other girls would not be able to perform at the Hyde Park event July 2. "It has got to be all or nothing," Sir Bob was quoted by the website as saying.

Mel has previously admitted she wants the girls to get back together - but not until 2006 to celebrate their 10th anniversary. The concert is to raise funds to help underdeveloped countries of Africa.