When the black township of Soweto erupted in an expression of uncontainable rage two years ago, the white press was effectively sealed off from covering the black community both by the police and by black suspicion.

Suddenly, was black journalists who were bringing out the details for the largely white press from the places where they lived and the people they lived among. And ultimately, they were reporting it for the whole world.

"The black journalist found himself in a new role," says Percy Qoboxa, former editor of the banned black daily, The World. "Their sheer guts and professionalism during those days gave notice that the black journalist had matured and is now arrived."

Indeed, it was a change.

Most black South African journalists had traditionally been consigned the role of "leg men," the unsung gathers of facts who turned over their notes to white reporters who generally got the byline - and the credit - for the story.

"Until Soweto blew up, many papers never felt they needed black journalists," says editor Clive Emdon. Most whites, isolated from the realities of black urban life, still think it cannot be as bad as blavk journalists say it is. White newspapers, long satisfied with the limited contacts they had among blacks, found differently.

Today the black journalist, once hindered by discrimination, enjoys a new-found prestige both among white colleagues and throughout the black community.

The new preeminence, however, has also brought new risks.

"The police resented their methods being exposed," says Qoboza, referring to the gripping details black writers were able to bring from Soweto. Consequently, the government has widened its interpretation of the legal term "incitement," and now pins this label on much black reporting.

"The truth to them is incitement," says Enoch Euma, 36, a veteran journalist, "and the security police have told me that black reporters are 'agitators.'"

That may well be the government's assessment, given the reasons the censorship board offered recently when it tried to ban The Voice, a black newspaper.

"Favorable publicity is given to the formation of a new militant black organization, the Azanian Peoples' Organization," the board argued, "and articles favorable to persons who have been restricted, detained or fallen foul of the law . . . evoke sympathy for them and their families, and hostility to the authorities."

Faced increasingly with government suspicion over what they see as just doing their jobs, black journalists have found just the opposite reaction in their own communities.

"In the past, people used to shun you, used to say, 'Journalists, oh, they are liars,'" recalls Sophia Temaa, 37, a veteran of 14 years at The World.

"It's different now," she says. "They will help you and even come on their own to tell you things. But they also put more pressure on us, too. They demand to know more from us and want us to inform them."

That demand, and new feeling of purpose, have had an effect. The black journalist, like his black readers, has been touched politically by the news of the past two years, sometimes in gruesomely real terms.

Hector Peterson, the first young victim of the student-police confrontation in Soweto two years ago, died in Temmaa's car, for example.

"A black journalist feels proud he is part of the struggle," Temmaa says. "We feel we are part of our people and are more dedicated to the cause. The very problems which affect my people effect me as well. I am not immune to or excluded from them."

While the new political feeling may have injected a new spirit into many black journalists, it also presents them with a conflict in roles.

"We are black people first, journalists second," says one young reporter."If it comes to a conflict between the struggle and the job, the struggle comes first."

Not all black journalistssee the conflict so clearly. Qoboza, for instance, who has spent his life pushing and testing South Africa's racial policies, was jailed last year when The World was closed. Tempered perhaps by experience, he sees it differently.

"It's been a terrible crisis for me personally," he says. "I've always emphasized that to maintain professional credibility . . . we must be journalists first and blacks second. Otherwise, we tend to lose sight of our real responsibility which is to inform people and give them the facts."

For many black journalists, making philosophical distinctions is becoming more and more difficult, however, as they increasingly become targets for what they term police harassment. Even Qoboza concedes that "it's a new ballgame as far as the police are concerned."

Reporters are called in for questioning, sometimes, unexplicably, about long - past assignments. Temaa was asked last year about something she covered in 1959.

Five black jo

Five black journalists are being held under South Africa's tough detention - without - trial laws, and photographer Moffat Zungu is being tried on charges of "terrorism"

To understand the pressure on black journalists, it is necessary to note that none of the white colleagues are currently under detention.

Inevitably, the new black journalism may produce a generation gap.

"Being a journalist is no longer a pleasant job just to enjoy," says "Doc" Sipho Bibitsha, 48. "It's an aggressive job now."

"They take us old journalists as softies, as moderates," he mused recently, staring into his lap through black - framed glasses. "They say we have been under the system for so long that we don't see things as they are. It does hurt."

With the heavy blanket of government repression, the detaining and banning of black leaders, the black journalist often emerges as an unwitting spokesman for the community.

A recent editorial in The Post, a successor to The World, stressed the importance of that role.

"Again it looks as though it is left to the press to protest against. . . encroachments on our country's vital freedoms," it said, "So let's spell it out again. We refuse to be intimidated. We have a job to do."

Doc Bikitsha has a sobering thought regarding that.