The squatters of Chiawelo share the District 9 limelight with another group on the bottom rung of society.

Nigerian immigrants play a large part in the film – taking the roles of gangsters, prostitutes or witch-doctors. They are depicted eating alien flesh or having sex with the creatures. Many Nigerians are furious.

An internet backlash is under way with an online petition and a Facebook group, "District 9 Hates Nigerians", accusing the film of xenophobia.

One blogger, Nicole Stamp, wrote: "That's Hollywood's Africa, isn't it. Black Africans shown as degenerate savages who'll have sex with non-humans and are pretty damn eager to eat people. Disgusting."

There was further criticism yesterday from the Nigerian-born British actor Hakeem Kae-Kazim, who appeared in the films Hotel Rwanda and Wolverine.

He told South Africa's Beeld newspaper that many Nigerians were upset about the film. "I have lived in South Africa," he said. "The country has so many beautiful things to offer … its problems can't be ascribed only to a small group of people."

On Facebook, he wrote: "If the African continent truly wants to be liberated, we cannot sit back and allow this depiction of a 'few rotten apples' to be spread across the world."

He expressed concern that District 9 would reinforce negative stereotypes of all Africans.

"The idea that it's not only Nigerians, but all Africans who behave in that way, will be spread across the world. I find that to be a painful thought. The manner in which the Nigerians are depicted cannot be justified."