The South African government has scrapped most of its controversial restrictive labor practices that legally excluded blacks from certain jobs, instead of reserving them for whites or persons of mixed race.

From the point of view of the National Party government which has always protected the job opportunities of the white population, yesterday's action could be seen as a "change in principle," according to one observer. In substance, however, legal move only affects about 2 per cent of he job market and, in fact, many of these jobs are already filled by blacks.

By far, the greater number of jobs "reserved" for whites and "coloreds" (mixed race persons) are not legislated, but are part of the contracts negotiated between the white and colored unions and their employers with the sanction of the government. These reservations, which affect virtually all skilled labor, remain.

In addition, the government did not repeal the restrictive clauses that apply to some of the more meaningful jobs. These are areas controlled by the strongest national unions, namely, the mining, automotive assembling and building industries.

In making the announcement, however, Labor Minister Fanie Botha noted these remaining legal restrictions were "urgently" being studied to determine if they were necessary.

The largest all-white trade organization, the 200,000 member Confederation of Labor, guardedly approved the minister's action but said this acceptance was conditional on there being "other measures which will protect the white worker."

Spokesmen for the independent black unions welcomed the changes, but characterized them as "not so significant."

They touch on jobs which we don't consider importand," said Henry Chipeya, secretary administrator of the Urban Training Center. "We tend to treat with caution all concessions by the government since we know they always in line with "its policy of separate development for the races.

Although blacks are allowed to form unions, the unions are not recognized for purposes of collective bargaining.

Earlier this year, the deputy secretary for labor, Johan Botha, said statutory job reservations affected about 2.3 per cent of the labor force, or 117.000 workers.

The jobs reserved for whites include elevator aperators (traditionally reserved for retired whites on pensions), drivers and jobs in the clothing, wholesale meat, liquor and refreshment, furniture and footwear industries.

In addition, the government announced that two categories of restrictions in the iron and steel industries that have been ignored for some time were move were supervisory and journeyman jobs in the restrictions because of what a Labor Ministry spokesman called "marked resistance to lifting the job restrictions" in those industries.

Important areas not touched by the government's move were supervisory and journeyman jobs, surveyors and supervisory slots in auto assembly plants.

Discriminatory labor laws in South Africa date back to the 1890s, but they were originally cast along educational lines. Twenty years ago the government legalized discrimination on a racial basis in order to protect traitionally white or colored positions from "infiltration of black people" who, as a Labor Ministry spokesman said, "were able to work for much less" money.