"There are a lot of illegal, under-the-counter products that people use that can be dangerous."
In 2008 it was claimed Beyonce's skin was digitally lightened in advertising for L'Oreal, an accusation the beauty company said was "categorically untrue".
In February last year, Yasmin Alibhai-Brown, who writes for the Mail, said she believed Beyonce was betraying black and Asian women after she was pictured looking paler than usual with long, straight blonde hair.
But Heidi Mirza, professor of equalities studies at the University of London, said Miss Knowles" image was developing "new forms of black style".
Beyonce, whose father is black American and mother mixed race, last week gave birth to her first child, Blue Ivy Carter. Her spokesman was not available for comment.
- Daily Mail