Melanie C has warned One Direction that they won't be global stars forever.

The group have enjoyed a massive 2012 as they broke America and released their second album 'Take Me Home'.

Speaking to heat, Melanie C said that her own experiences in the Spice Girls during the 1990s have taught her that the pop world is fickle, with success not guaranteed to last. She said:

"They seem to be breaking America, which we were lucky enough to do. My advice would be just enjoy it, because so often with success like that, it's over so quickly."

Giving advice, Sporty Spice added: "Really enjoy every minute of it. Try and take it all in, because it's crazy. With pop bands, [fame] is often so short-lived that you have to take every opportunity that you can, and it is hard."