Naomi Campbell admits it is a ''challenge'' to work alongside younger models as she approaches her 50th birthday.

The 48-year-old beauty has been working in the fashion industry for over 30 years and has admitted it isn't easy to be as in-demand as she ever has when there are so many young catwalk stars breaking into the business.

In an interview with the new issue of Grazia magazine, she laughed ''I am now 48 so to be in the same show as a 16 year old is a challenge for me.''

Naomi uses a personal trainer to oversee her daily workouts in order to stay in the best shape she possibly can.

She said: ''I have to work out, I do a combination of HIIT training and boxing.''

Away from her modelling career, Naomi has launched Arise Fashion Week - a three-day festival in Nigeria - and did so on the urging of her late friend Nelson Mandela, though she admitted it has taken until now for her to have the ''confidence'' to do what he wanted.

She said: ''I feel that he was trying to tell me to do this, but I really didn't understand it when I was younger. I didn't have the confidence. When he passed away, I felt a little lost, but his words always stayed with me. I remember all the things he would say to me so this now feels like a natural progression. Fashion is where I come from, so I started with my industry.''

And Naomi thinks Africa ''deserves'' to be ''spoken about'' within the fashion industry because there are so many talented people on the continent.

She said: ''This is a continent that has been untapped and ignored.

''There is so much emerging talent here that has struggled for so many years, it needs to be spoken about.''