JOHANNESBURG, SEPT. 2 -- A militant black antiapartheid group demanded today that director Richard Attenborough allow it to censor his forthcoming film, "Cry Freedom," which tells the story of Steve Biko, the founder of South Africa's black consciousness movement who was killed while in police custody.

The Azanian People's Organization, which considers itself the only true heir of Biko's political legacy, threatened to launch an international campaign against the film if Attenborough refuses.

Muntu Myeza, the group's spokesman, said that from what had been seen of the script and early scenes, the film grossly distorts black consciousness and Biko's politics and that its focus -- white South African newspaper editor Donald Woods -- is "a liberal nonentity."

Myeza said a "black consciousness delegation" had already made a number of objections and won some concessions during discussions earlier this year with Attenborough, director of the Oscar-winning film "Gandhi."

The group would now try to see Attenborough again, Myeza added, to seek further changes before the film is released in the United States and Britain in early November.

"What the black consciousness movement is saying exactly is that no one can make a move on Steve Biko without our blessing," Myeza told a press conference. "The content of the movie must have our sanction where it refers to or purports to represent what Steve Biko thought and what he did."

Attenborough could not be reached immediately for comment, though he said earlier this year that he welcomed constructive suggestions from Biko's associates in the black consciousness movement.

Biko, one of the most charismatic black leaders to emerge in South Africa in the past three decades, died Sept. 12, 1977, of head injuries sustained while in police custody. He had apparently been beaten and tortured while detained without charge under South Africa's security laws and had been driven 700 miles from Port Elizabeth to Pretoria, naked and manacled, in the back of a police car. A magistrate ruled that no one was responsible for his death.