Hudson's promise over Winnie film
Jennifer Hudson has insisted her latest film will give an unbiased perspective of Nelson Mandela's ex-wife.
Winnie, which will star Oscar-winning actress Jennifer in the title role and Terrence Howard as the former South African president, starts filming in South Africa on May 31.
But Ms Madikizela-Mandela, as she has been known since her divorce, is understood to be unhappy about the biopic, which is based on Anne Marie du Preez Bezdrob's biography, Winnie Mandela: A Life.
A spokeswoman for the film said its producer Andre Pieterse and director Darrell Roodt had met lawyers representing Ms Madikizela-Mandela and had refused to give her script approval because they wanted to preserve the integrity of the film.
Speaking in Cannes, Jennifer, 28, insisted the film would let movie-goers make up their own minds about the controversial figure.
"I feel like it's not biased at all, one way or the other," she said.
"It puts it out there for you to decide on your own, but it does put it out there, and I think that's the important thing."
The actress said it was an "honour" to be cast in the lead role.
She said: "There's definitely a story that's worth being told, and I'm still shocked that I get to be a part of this and I get to portray this role. It's just such an honour."
Ms Madikizela-Mandela remains a contentious figure in South African history - she was considered key to the anti-apartheid struggle, but was later convicted of fraud and theft.