The advert by its TRESemmé brand, was posted on drugstore Clicks Group's website last Friday, and described images of African black hair as "frizzy and dull," while a white woman's hair was referred to as "normal".

It caused an outcry on social media and sparked protests led by the opposition Economic Freedom Fighters (EFF) in a country where unfair treatment of black hair evokes painful memories of prejudice during apartheid.

The then-government used a "pencil test" to determine someone's racial identity: a pencil was inserted into a person's hair and if it did not fall, that person was considered not white.

"We were shocked to discover that we had supplied images for the Clicks website that portrayed black hair as inferior. This was racist and we apologise unreservedly," Unilever said in a statement.

The firm is reviewing all the marketing campaigns and images in its South Africa portfolio "to make sure they match our commitment to celebrate all beauty and promote diversity and inclusion."

It will also set up a new diversity and inclusion assets committee and an advisory board with internal and external experts to review how its hair care products in South Africa can offer consumers solutions, it said.

The household goods conglomerate behind the Omo, Sunlight and Domestos brands will also work with the new advisory board to develop programmes to deliver immediate support to black hair stylists and small professional salons.

Lastly, Unilever will review its mandatory diversity and inclusion training to accelerate its training on unconscious bias for all staff.

On Thursday, Unilever agreed to pull all its TRESemmé haircare products from South African retail stores for 10 days to show remorse after some retailers had begun removing the products.

(Reporting by Nqobile Dludla;Editing by Elaine Hardcastle)