London: British pop girl group Spice Girls is reportedly planning a reunion concert at Hyde Park here next year. According to a source, members Melanie Brown, Geri Halliwell and Emma Bunton are already onboard the project, reports aceshowbiz.com. "Mel B, Emma and Geri agreed Hyde Park would be the ultimate way to launch a reunion next July for their 21st anniversary," the source told The Sun newspaper. "It gives them a year to plan everything and make sure their comeback is spectacular. It would be the most-talked about gig of the year," the insider added.