A film about a black girl born to white parents in apartheid South Africa symbolises the "appalling" nature of the system, according to its star.

A film about a black girl born to white parents in apartheid South Africa symbolises the "appalling" nature of the system, according to its star.

Sophie Okonedo said Skin summed up the "ridiculousness" of the country's former segregation policies.

Based on a true story, the film follows the life of Sandra Laing, who was born in the 1950s to Afrikaner parents - the difference in skin colours believed to be due to some kind of genetic throwback in their ancestry.

After being expelled from her all-white boarding school at the age of 10 and classified as "coloured", her parents, Abraham and Sannie, fought for her to be reclassified as white. But Laing was later rejected by her father when at 16 she began a relationship with a black man.

The film, directed by Anthony Fabian, charts her struggle to find her place in a society torn apart by race and politics.

Attending Skin's UK premiere in London's Leicester Square last night, Okonedo - dressed in a £5.99 dress from Oxfam - said: "I couldn't believe it was true. I was like are you sure?' "It's such an extraordinary story and it's so symbolic of that time. It was appalling, the ridiculousness of the apartheid system.

"The story just shows it the system up for what it was."

Herself the daughter of a white mother and black father, the Rada-trained actress, who was nominated for an Academy Award for Hotel Rwanda, added that attitudes in London were now more laid-back than in the 1970s when she was growing up.

"It was different then," she said. "There was much more overt racism."

Sandra Laing also attended the premiere at the Odeon West End, visiting the city for the first time.

She described how her life had changed for the better since work on the film began nine years ago.

Laing, 53, said: "The film has changed my life a lot.

"When I met Anthony Fabian I was staying in a rented house and I didn't have a phone, but since I met him my life is much better.

"I am just glad there was somebody who would tell my story about how I suffered through the apartheid years."

The married mother of five, who has seven grandchildren, described her parents as victims of the system. She was finally reunited with her mother in 2000.

Skin will go on general release in the UK on July 24.