A growing militancy among 6 million black workers has given South Africa its most prolonged industrial unrest at a time when the government has begun to make some limited reforms in the black labor structure.

Black workers throughout the country are increasingly joining black labor unions, demanding higher wages and union recognition from their employers, and resorting to wildcat strikes without union approval if their demands are not met.

Over the past year, work stoppages and strikes have involved skilled workers in the automotive manufacturing industry, illiterate migrants in slaughterhouses, farm workers on the country's largest citrus plantation, construction workers on the strategic oil-from-coal manufacturing complex and, for the first time, certain municipal government employes.

A better-educated, more politicized work force is beginning to recognize its increasing importance as it moves into skilled positions that whites can no longer totally occupy in an expanding economy.

Most labor observers here see the stage set for a protracted struggle in the 1980s between this increasingly militant black labor force that accounts for 67 percent of the country's workers, and a government seeking to control it through a combination of authoritarianism and reform.

The black trade union movement is regarded by many as a more potent force for change in South Africa than any guerrilla action, rioting or political protest. In an effort to ensure industrial peace, the observers argue, the government will have to come to terms with strong black unions and their militant members, and give them a measure of real collective bargaining power.

Before this year, black unions were tolerated, but never officially recognized by employers met on an industry-wide basis to discuss wages, benefits and working conditions. The black unions had to be content with waging their battles at individual factories if an employer allowed them in. Any agreement they reached with an employer was not legally enforceable.

Nevertheless, the independent black labor movement grew to include 100,000 workers organized into approximately 30 unions.

The key reform of the government's "new deal" for black labor has been the recognition that black unions are here to stay, and that the government would fare better by bringing them into its official industrial conciliation machinery, through which they could be controlled.

Although recognizing the right of black workers to unionize was a significant change, it has presented the black trade unions with a dilemma. If the decline to join the government's formal machinery and to become "registered" union, they forfeit official recognition and face continued employer reluctance to deal with them.

However, by registering they would give up a certain measure of the independence they have enjoyed, because the government would have access to their financial records and would have to approve their constitutions.

In addition, black trade unionists -- as well as independent labor analysts here -- have misgivings about the capacity of the existing industrial conciliation structures to meet the new needs of the 1980s without further reforms.

"They took a 1922 Olds and tried to make it into a 1980 Ferrari," said one Western labor observer.

Up to now, that machinery has existed for a privileged and skilled white-minority work force operating in a political climate that guaranteed them jobs. Now it is expected to cater to the needs of a black proletariat of mostly unskilled and semiskilled workers who do not have labor mobility because of apartheid laws restricting where they can live and because of widespread unemployment.

As a result, black workers are demanding unions that can provide them with vigorous job protection. Because they lack political rights, they are also demanding that unions aggressively address a wide range of social and economic issues when they meet employers and government officials.

Black unions, therefore, want and need to continue to have a strong presence in shops and factories, and direct contacts with employers. But in the government-approved machinery -- in which trade unions have their regular contacts with employers on industrial councils and in which controls will limit the actions of black unions -- their presence in shops and factories will have less impact.

In this way, the government hopes to dampen the militancy of black unions and keep them from being politicized. "They want to have Russian-type trade unions," said one critic of the government's labor reforms.

In addition, black labor organizers object to the cumbersome and complex grievances procedures of the government machinery. "They are so intertwined with the red tape that they are virtually meaningless," said black unionist Henry Chipeya.

"No genuine trade union believes in them. They are seen as government tactics to delay the workers' grievances being heard," he said.

To complicate matters, existing white trade unions, with government encouragement, are setting up affiliate black unions with "moderate" leaders to woo workers from the existing black unions that are regarded as "militant" and "radical."

As a result, these so-called "parallel" or "stooge" unions and the "independent" ones are vying to be registered or recognized by the government. So far, all the black unions that have been registered have been "parallel" unions.

This effort was most blatant in the Johannesburg municipal workers" strike in July, when 10,000 strikers were demanding recognition from the City Council for their newly formed black union. Instead, the union leader was arrested by police, the City Council refused to speak to union officials and the government stepped in with formal recognition for a rival union set up with the help of the council's white personnel staff. The recognition came in what one black unionist called "a record time of two weeks" from the date of its application. I had 40 members at that time.

Many employers, perhaps more perceptive than the government, are saying that their first concern is not whether the union is acceptable to the government, but whether it is representative of the workers and can discipline them.

Ford Motor Co. learned this during its strike last November.The workers shunted aside the union, with which Ford had good relations, because it was not militant enough. Ford now has allowed the union's shop stewards to work on union business full-time so that it can build up the broken lines of communications.

"We would say the most important question is the representativeness of the union," said John Van Zyl, executive director of the 10,000-member South African Federated Chambers of Industry. If a union is not officially "registered" by the government, but still represents most of the workers, employers "cannot just close our eyes to it," Van Zyl said.

The recent labor unrest "has shaken industry up considerably," Van Zyl said. "It's amazing the extent to which they are waking up to take a long, hard, pragmatic look at relations with labor.

"Employers, employes and government are moving toward some better style of being together. We certainly are learning that some things are not working.Fundamentally, we still have a lot to learn about handling strikes and that applies to both employers and labor," he said.

One of the issues that must be resolved if the government's labor reforms are to have any meaning is the role of the police. Although one of the government's reationales for its labor reforms was that they would depoliticize labor conflict, it was permitted the police to become involved in many of the past year's strikes.

Five union officials were detained without charges during a meat workers' strike in Capetown. Eighteen Ford workers were arrested, and Ford strike leader Thomazile Botha was detained, then forced into exile, Johannesburg municipal strike leader Joseph Mavi was detained. He is now out on bail while police investigate a sabotage charge against him. Armed police escorted fired Johannesburg municipal workers back to their rural homes in buses and beat them on the way, according to workers.