JOHANNESBURG, SEPT. 18 -- Winnie Mandela, wife of African National Congress leader Nelson Mandela, will be tried on charges of kidnapping and assault in connection with the 1989 death of a young black township activist, the attorney general of Transvaal province announced here today.

The decision to put on trial the wife of South Africa's most famous black leader came less than six weeks after a Transvaal court sentenced to death Jerry Richardson, coach of the Mandela United Football Club, for the murder of Stompie Seipei, 14.

Seipei was kidnapped and taken to Winnie Mandela's home in Soweto, where he was beaten and then taken away and stabbed to death on Dec. 31, 1988, or the following day. He was suspected of being a police informant.

Nelson Mandela was still in prison -- he was released Feb. 11 after serving 27 years on a sedition charge -- and Winnie Mandela was using members of the club as bodyguards and sometime enforcers of her rule in the struggle among rival black groups in Soweto, according to testimony given at Richardson's trial.

It was not immediately clear what effect the state's action would have on the ANC, whose leadership already is bitterly divided over the wisdom of having recently appointed Winnie Mandela as head of the organization's social welfare department.

Winnie and Nelson Mandela were attending a two-day meeting of the ANC's National Executive Committee, and neither had any immediate comment on the announcement by provincial Attorney General Klaus von Lieres.

A statement issued by ANC Secretary General Alfred Nzo said the organization did not seek "any special treatment" for Winnie Mandela but protested what he called her "trial through the media."

Any comment while her case was before the courts would be "improper," said Nzo, but the ANC National Executive Committee affirmed "its unequivocal support" for Nelson Mandela and his family "in this time of stress."

Both Mandelas had complained that the government was seeking to "defame" Winnie Mandela by allowing witnesses during Richardson's trial to implicate her in Seipei's death without giving her a chance to respond.

In fact, on advice from her lawyer, Winnie Mandela refused to testify at that trial. But she and her husband indicated they would welcome the opportunity for her to clear her name in court.

Three youths kidnapped with Seipei testified at Richardson's trial last May that Winnie Mandela was present and had struck the first blows in an interrogation conducted at her Soweto home.

Von Lieres said in his statement that she would face charges on four counts of kidnapping and four of assault with intent to commit grievous bodily harm -- the same charges that Richardson faced and that led to his Aug. 8 death sentence.

The attorney general said Winnie Mandela would be tried with seven others already charged in the Johannesburg Supreme Court and that the same witnesses who had testified against Richardson would testify on the state's behalf against them at "an early trial date."

"In various quarters it has been claimed that Mrs. Mandela has been unjustly victimized by being refused an opportunity to defend herself. During a recent visit to the United States, she has been reported in the press as having said that 'she would welcome being charged in the murder of Stompie' so that she could appear in court to defend herself," von Lieres said.

"My decision to prosecute Mrs. Mandela was taken not in response to these various claims and statements," he said, "but because of my understanding of the facts, the law of the land and my duty as attorney general to uphold and apply the law to all alike." If she cooperates, "there will be no need to resort to strong measures to ensure Mrs. Mandela's attendance at court," he added.

ANC officials and other analysts here disagreed on whether the government was seeking to intensify already considerable divisions within the organization to weaken its negotiating position in forthcoming consitutional talks.

Von Lieres has the power to decide which cases to prosecute within his jurisdiction. But in this case it is thought probable that he consulted President Frederik W. de Klerk's government.

Some analysts felt the government might have been motivated to act against her now because of the controversy raging within the ANC over her appointment in mid-August as head of the organization's social welfare office.

The decision was opposed by many internal ANC officials, who questioned her judgment in becoming so deeply involved in the Mandela Football Club scandal. They regard her appointment -- proposed by ANC Secretary General Nzo -- as the work of the external "old guard" leadership recently returned from exile in Lusaka, Zambia, and out of touch with grass-roots sentiment. Nelson Mandela is said neither to have promoted nor opposed her nomination.

Some analysts felt, however, that the state was faced with a no-win situation in trying to decide whether to prosecute. Given the strong testimony implicating Winnie Mandela in Seipei's death, a decision not to act, they said, would also have been regarded as political -- to avoid subjecting Nelson Mandela to the embarrassment of seeing his wife tried.