JOHANNESBURG, FEB. 4 -- The long-awaited trial of black activist Winnie Mandela began today in the Rand Supreme Court with her defense lawyers demanding dismissal of all kidnapping charges against her stemming from a 1979 case in which she also faces assault charges.

Chief defense attorney, George Bizos, who defended her husband, African National Congress leader Nelson Mandela, in his 1963-64 Rivonia treason trial, charged that the state had refused to disclose enough information about the kidnapping charges to make it possible for him to properly defend her.

"Precisely what act or acts did Mrs. Mandela perform to deprive the complainants of their liberty? Precisely when and precisely where were such acts performed by her?" Bizos asked. "She is clearly entitled to succinct information on each question."

Bizos also told Judge M. S. Stegmann that if he found some of the charges against any of the codefendants to be faulty, then he should separate their cases.

The prosecution's chief lawyer, Transvaal Deputy Attorney General Jan Swanepoel, asked for a postponement until Tuesday morning to prepare his rebuttal.

The initial defense strategy seems aimed at forcing the state to disclose more of its evidence against the accused at the start of the trial as well as to separate the cases, a procedure that would require a delay in the formal start of proceedings.

Winnie and Nelson Mandela, who was in prison at the time the alleged crimes took place, arrived at the downtown court building nearly an hour ahead of the start of the trial. Both were smiling and appeared relaxed over what could become a major ordeal for her family and the ANC, the leading black nationalist organization in South Africa, if she is found guilty.

Many senior ANC officials, including Alfred Nzo, Chris Hanni and Joe Slovo, turned out for the opening session of the trial and sat alongside Nelson Mandela in the third row. If she were to be found guilty, the ANC would have to decide whether she should relinquish her various national and regional leadership posts in the organization.

There was no crowd outside the court building to greet them this morning and the atmosphere inside the small, wood-paneled trial room on the fourth floor was somber. But when the court broke for lunch the Mandelas were greeted with cries of "Viva, Viva, Viva" and clenched fists from a small group of supporters.

Mandela has been indicted with seven others on eight counts of kidnapping and assaulting four Soweto township youths in 1989. One of the youths, 14-year-old "Stompie" Moketsi Seipei, was later murdered. Mandela has not been charged in the murder.

The state has alleged that the youths were taken to Winnie Mandela's Soweto home from a church hostel and beaten there -- in her presence -- before Seipei was taken away and killed.

Jerry Vusi Musi Richardson, the leader of her now defunct bodyguard unit, known as the "Mandela United Football Club," was tried and convicted last year of murdering Seipei, alleged to be a police spy by the football club.

Only three of Mandela's seven codefendants showed up for the trial and Stegmann issued a warrant for the arrest of the others and confiscated their bail. None of the defendants was asked to plead today.

The state has charged all eight with four counts of kidnapping plus four charges of assault.