Geri Halliwell says she was holding back the tears when she watched the workshops of the new musical.
Mel C added that the rehearsals gave the girls "goosebumps" and it was a "lovely thing"
The girls said the musical supports Girl Power's longevity. "Who would have thought the message is still standing 16 years later".
More top news
Strong winds, heavy rain and snow forecast across the UK
Police are hunting a man suspected of trying to set Finsbury Park Mosque on fire earlier this morning
A company which specialises in electronic toys and educational material for children has revealed it has been the victim of a cyber attack.