For the past three weeks South African authorities have been presenting evidence in a packed courthouse, trying hard to show that a group of former students fomented by "agitators" were responsible for 16 months of black unrest sparked by the 1976 Soweto riots.

But the 11 defendant trial for sedition charges stemming from the June 16, 1976, riot say the trial is serving the opposite purpose by once again illustrating black frustration in this racially segregated society.

The spirit of the defendants, who sport look-alike track suits in court, appears to remain undaunted, despite the fact that the trial is expected to last six to 12 months and is being held 35 miles from the black township of Soweto to reduce the attendance of friends and family in the courtroom.

"We think this trial is fine, so that the true-feelings of blacks can come ut, otherwise it will all be buried and forgotten," said defendant Susan Sibongile Mthembu.

"It must be shown that the unrest was not caused by a bunch of rowdy children, but by legitimate grievances and complaints of the people," one of her defendants said.

But for many of the spectators, listening to the testimony is like reliving a nightmare," one woman in the gallery said.

The defendants ranging in age from 18 to 23, are accused of helping organize, through their association with the new banned Soweto Students Representative Council, student protests against their inferior and segregated education system and the use of the Afrikaans language in the schools. Government officials say the protests were designed to undermine the authority of the police and the Department of Bantu (black) Education.

The rioting shook the confidence of the white government and brought it heightened international criticism for its racially based policies. South Africa is anxious to present, especially to overseas investors and critics, an identifiable reason for the unrest other than its own unequal political and economic systems.

The students on trial were all held in solitary confinement from seven to 12 months before they were formally charged in July. Some of them, including the former leader of the students council, Daniel Sechaba Montsitsi, were tortured or beaten while being held incommunicado by the security police, according to reliable reports. The authorities deny that Montsitsi was admitted to the hospital during his pre-trial detention, and his family and friends say only that they see a marked change in his personality.

Some of the witnesses scheduled to testify against the defendants are still being held by police until their day in court.

In the initial days of testimony, white policemen and government workers described their experiences during the first student demonstration.

Juvenile employment officer Rudolf Hobkirk told how a crowd of students burst into his Soweto office and tried to beat him up. He was saved by a young black girl who shoved him into a storeroom and locked it, he said. But while inside, Hobkirk said, he could hear white social worker Melville Edelstein being fatally beaten.

Another witness, Soweto police officer Johannes Kleingeld, said his men were equipped only with guns when the riots broke out. Under cross-examination by defense lawyer Ernest Wentzel, who helped represent the family of Steve Biko at the inquest into the prison death of that black consciousness leader, Kleingeld told his men not to retreat out of fear the police would "lose face." In the confrontation that followed 13-year-old Hector Peterson was fatally shot by police.

The students on trial are only a handful of the thousands who were involved in the protest of 1976 and 1977. Most of their colleagues have fled the country to avoid arrest. This trial is one of the most important of the more than 60 political or "security" trials initiated this year by South African authorities.

Former Prime Minister John Vorster in 1976 ordered a special one-man investigation of the Soweto riot. Although the investor, Justice Petrus Cillie, has completed his hearings, his report is not completed yet. A spokesman for Cillie said it is "difficult to say when it will be finished."

Some government critics harbor suspicious that the Cillie report has been delayed on purpose because its recommendations and findings might jeopardize the state's case against the 11 defendants.