Eight men, six of them police detectives, went on trial here yesterday in the death of one black prisoner and the alleged beating of five others last March.

Mistreatment of blacks held by South African authorities has drawn world attention since the death last year of black leader Steve Biko, who was severely beaten while in detention. At least 26 blacks have died while in police custody in South Africa in the last two years.

Two white and four black detectives and two white civilians pleaded innocent to murder and assault charges here yesterday.

Prosecutor A. R. Erasmus said that those charged had suspended six naked black prisoners by chains from a ceiling and subjected them to beatings and electric shock treatment after arresting them on suspicion of burglary.

Eight days after the alleged beatings, one of the prisoners, Jankie Mahlomola Matobako, died in a hospital.

After the six had been arrested, Erasmus' statement said, "they were hanged naked by their wrists. As they hung, they were hit with a leather whip and hose pipe."

Erasmus said wires then were applied to their bodies for electric shocks.

A surgeon who examined Matobako in the hospital testified that "he was in a state of shock and pain. He had 18 long bruises on his back and eight on his chest.

"There was swelling on his arms, forearms and head, and bruises on his left shoulder and at the top of both legs. There was swelling and bruising of his whole face and one eye."