Strikes shatter S. Africa calm. Violence is biggest challenge to Pretoria since crackdown

Black strike action, a form of protest relatively unfettered by South Africa's state of emergency, is presenting the authorities with its most assertive challenge since the clampdown began 10 months ago. A flare-up yesterday showed no immediate sign of spiraling into unrest on the scale of the pre-emergency period. Moreover, one expected short-term effect was to rally support for the governing National Party in a white election set for May 6.

Still, twin acts of black protest in the Johannesburg area demonstrated a defiance absent in black politics for many months. The actions included:

A refusal by an estimated 16,000 black strikers from the state-run transport services to return to work or be fired.

A work and school stay-away by thousands of other blacks in the commuter township of Soweto. This followed distribution of anonymous pamphlets earlier this week advocating a protest against the planned eviction of rent-strikers.

Both actions ended in violence. Police clashed with two separate groups of demonstrators from the transport union in the Johannesburg area, leaving at least four blacks dead, according to the government's Bureau for Information. One of the victims was killed in a clash in Germiston, a Johannesburg suburb, and the others at a central Johannesburg train station. Officials said the police had opened fire there after at least two policemen had been injured by demonstrators.

Inside Soweto, tear gas was reportedly fired on a group of blacks who marched on town council offices in connection with the rent dispute. No casualties were reported.

The authorities are clearly aware of the potential problem presented by labor unrest. Black unions, legalized seven years ago in a key government reform, are well organized and, since the emergency, increasingly militant on political issues that transcend the workplace. They possess - through member workers essential to the country's economy - far greater potential leverage than other black organizations. The unions have managed to secure a degree of immunity from state-of-emergency restraints, by impressing on management a shared self-interest in keeping recognized labor leaders free to operate.

Thus, it was not until two days ago that the transport authorities intervened in the month-long strike - despite the fact that such public-service strikes are illegal, and despite a series of apparently strike-related arson attacks on parked train coaches. By threatening to fire workers who did not return to the job, the management apparently reckoned that the combination of a proven government determination to ``restore law and order'' under the emergency, and of widespread black unemployment, would give teeth to the ultimatum.

That calculation may yet prove justified. Even before the announcement of the emergency last June, protests by black workers were limited by fears of unemployment or reprisal.

Similarly, officials say that under the umbrella of the emergency, many Soweto blacks have quietly resumed paying rent to local authorities, breaking with a protest that has raged intermittently in various black townships for more than two years. It is this break, presumably, that has given officials the confidence to start evicting hold-outs. Some six months ago, an earlier eviction attempt in Soweto provoked the single most violent clash since the emergency, leaving nearly 20 people dead.

Still, both the strikers and the rent protesters yesterday seemed prepared to defy official political calculations. Moreover, the trouble came only days before two events that could provide a focus for further unrest.

A persistent demand by black militants during the unrest that began in fall 1984, has been that the government recognize May 1 - as do the Soviet bloc and a number of Western nations - as ``international workers' day.'' Moving to defuse such pressure, President Pieter Botha recently declared that the first Friday of each May would be a national holiday - a day that falls on May 1 this year. But black labor leaders have said this is not good enough, and that they will continue to insist on the yearly celebration of May Day.

The second potentially problematic event on the political calendar is the May 6 election. It is for whites only, and some black leaders have denounced this as a reminder of black exclusion from the national franchise.

This report was written in conformity with South Africa's press restrictions.