A NATIONAL anti-apartheid protest campaign against South Africa's Sept. 6 election has all but overshadowed the crucial race for seats in the white and mixed-race parliaments. Leaders of the national defiance campaign - organized as a disciplined series of protests against segregated facilities - appear satisfied thus far with their efforts to heighten white awareness of black aspirations.
But the effectiveness of the campaign could be threatened by the eruption of sustained street violence in the politically volatile western Cape region.
And, in a security crackdown Wednesday night, an undisclosed number of activists were detained by police. A Law and Order Ministry spokesman said police acted against those who had defied restriction orders under the defiance campaign and who had ``threatened public safety.'' He added police were holding some in connection with ``the planned disruption'' of the election.
Independent sources indicated that at least a score of black trade unionists were held in the latest swoop. Police raided the Johannesburg headquarters of the Congress of South African Trade Unions (COSATU), the major black union federation, early Thursday and detained at least a dozen officials, including members of the biggest black trade union, the National Union of Mineworkers.
In the past two weeks police have detained three key anti-apartheid leaders under the 3-year-old emergency, including Mohammed Valli Moosa, acting general-secretary of the United Democratic Front, and Trevor Manuel, publicity secretary of the UDF in the western Cape. A third UDF activist, Willie Hofmeyr, was admitted to a hospital early Wednesday after a two-day hunger strike in his detention cell.
Meanwhile, as candidates of the three major white parties have addressed political meetings nationwide, black and Colored (mixed race) youths in the segregated neighborhoods of Cape Town have engaged daily in battles with heavily armed police.
The center of the sustained resistance in Cape Province is the Colored University of the Western Cape, where militant students - wearing masks and displaying the flag of the outlawed African National Congress (ANC) - taunt police at the campus entrance. Police have several times fired tear gas onto the campus.
In the streets of the desolate mixed-race townships, students stone and gasoline-bomb cars and delivery trucks and erect burning barricades in the streets.
Police have responded with shotguns, whips, tear gas, and dogs. According to figures released by the South African police, eight people have been killed in the violence of the past two weeks.
``The street violence of Cape Town detracts from the more dignified protests and actions [of the defiance campaign] and hampers organization,'' says Mark Swilling, a political scientist at the independent Center for Policy Studies in Johannesburg.
In a sermon Sunday in the Colored township of Silverton, Archbishop Desmond Tutu called on the militant Cape youths to stop their violent actions.
``Our cause is too noble to be undermined by ignoble methods,'' he said. ``We have no power, but God gives us a moral authority. So let us not spoil a good thing.''
Mr. Tutu appeared to be expressing the private fears of some anti-apartheid leaders that the relatively uncontrolled resistance in the Cape could damage the moral advantage won by the nonviolent actions against apartheid laws.
``It was an act of statesmanship on Archbishop Tutu's part,'' says Michael Savage of the University of Cape Town's sociology department.
The popular resistance in the Cape has called forth the toughest police response in the country. But the level of violence on both sides has been restrained compared to that at the height of a nationwide black uprising in 1985.
Yet sociologists warn that the Cape violence is serious and could erupt into a full-blown confrontation at any stage.
``What we are seeing in Cape Town is the meeting of two irreconcilable forces,'' says Professor Savage. ``The police have been very provocative in their actions.''
Last Wednesday, police arrested 170 women of the restricted Federation of South African Women when they tried to march from a prayer service in a Cape Town church to the British Embassy to deliver a petition concerning arbitrary detentions.
Those arrested included Leah Tutu, wife of the archbishop; Dorothy Boesak, wife of the Rev. Alan Boesak, President of the World Council of Reformed Churches; and Mary Burton, president of the Black Sash, a civil rights group consisting mainly of white women. The women were released several hours later after being charged by a special court.
A week earlier, Archibishop Tutu was among several clerics tear-gassed by police in the black Cape township of Guguletu after they had addressed a protest meeting in St. Mary's Church.
The violence in Cape Town is being attributed to several causes. The prevalence of criminal gangs in the Cape region contributes to street violence, analysts say. And, says Savage, the fragmentation among anti-apartheid groups makes it more politically volatile than other areas.
Black and white neighborhoods in the Cape are in close proximity, and tens of thousands of Colored have experienced forced evictions under residential segregation laws.
Another factor stirring militancy is the presence of the white-dominated Parliament, in which Coloreds and Indians were accorded segregated houses in a junior power-sharing arrangement in 1984. A large section of the Colored community remains vigorously opposed to taking part in elections for the Colored house.
Several mixed race and Indian candidates have been the target of arson and bomb attacks, and anti-apartheid leaders have demanded a total boycott of the Colored and Indian elections.
The election focus of the anti-apartheid campaign has posed a dilemma for the authorities.
The defiance campaign has elicited a strong response from police as it carried out protests against segregated hospitals, busses, and beaches.
The resistance is likely to reach a climax in the coming week, culminating in a nationwide strike by blacks on election day. But trade union leaders are already making plans to ensure that the defiance continues after the election.
``The aim of the mass democratic movement is to destroy apartheid,'' says trade union leader Moses Mayekiso. ``We are satisfied with the process so far.''