Iman will boycott designers who refuse to feature black models.

The 62-year-old supermodel has been in the industry for over 40 years and believes the best way to combat the lack of diversity in the fashion world is for high profile models to avoid supporting designers who aren't inclusive.

Speaking to Harper's Bazaar, the Somali-born beauty said: ''If a designer boycotts me, I should boycott him. I'm not going to buy a bag from someone who doesn't use black models. We should celebrate and highlight the people who actually step it up.''

When Iman - who is the late David Bowie's widow - first began her career, she admitted to being treated like a ''trend'' because of the colour of her skin but teamed up with supermodel Naomi Campbell to advocate change for the future.

She explained: ''People thought of fashion as something artistic and personal, but then it became more of a big-business machine. Casting agents have assumed an outsize power as gatekeepers. Some had the audacity to say, 'We're not seeing black models this season.' As if black is a trend.

''Funnily enough, there were more black models working back when I started than there have been recently. So Bethann Hardison, Naomi Campbell, and I got together a couple of years ago to raise awareness about the need for diversity in fashion. We talked about it in the press and to the CFDA, and I think we're seeing the change on the runways and in campaigns.

''Image is so important. People used to say to me, 'You just want to be invited to the table.' And I'm like, 'F***' the table - I can buy my own table.' But the young girls who are coming up? They need to see themselves portrayed.''

And Iman lives by the advice her mum taught her when she was younger and says her tip for a successful career is to say no.

She said: ''My mom always said, 'Learn to say no and to walk away from things that don't serve you.' 'No' is a complete sentence. You don't have to explain yourself.''