A Thai cosmetics firm has withdrawn its video advertising a skin-whitening product after it was attacked on social media for being racist.The company behind the product, Seoul Secret, issued a "heartfelt apology" saying it had not meant to offend.The incident has reignited the debate about attitudes to skin colour in Thailand.At that point her skin turns almost black, and a young, and very white, rival appears by her side. She looks down in dismay at her dark complexion and muses "if I was white, I would win".The advert stirred up a storm of debate online, with many Twitter users critical of the advert itself as well as the decision to withdraw it.Seoul Secret quickly withdrew the advert, although it could still be seen on YouTube on Friday, and offered a swift apology."What we intended to convey was that self-improvement in terms of personality, appearance, skills, and professionalism is crucial," the firm said.