PRETORIA, SOUTH AFRICA -- After a year of discreetly maintaining a low public profile, U.S. Ambassador Edward J. Perkins is beginning to stir anger in the South African government by calling for a political system that fairly represents the black majority.

While friction between Perkins, Washington's first black ambassador to South Africa, and the government of President Pieter W. Botha is still in an incipient phase, South African officials say they are closely watching the envoy's public statements for signs that he may become more aggressive in condemning the pace of reform of the country's apartheid system of racial separation.

On Friday, the South African Foreign Ministry took the unusual step of warning Perkins to stop interfering in the country's domestic affairs, saying that "how the present or any future government of South Africa sees its future is none of his business."

The statement, issued only in Afrikaans and carried mostly by progovernment newspapers, was in response to press inquiries following the publication of an article by Perkins in Leadership Magazine, a forum for the views of South Africa's leading opinion-makers.

In the article, Perkins called apartheid "one of the century's most disastrous feats of social engineering," and came close to calling for a system of one-person, one-vote, which Botha's government has said it will never accept because it would lead to the destruction of South Africa.

"A valid political system here must be one that correlates with the demographics of the country," Perkins said, "a government which truly represents the majority of South Africans."

Perkins added, "The majority must have a significant say in how that government is formed. I do not think elaborate schemes which try to give an impression of black representation, but actually maintain white power, will work."

He was apparently referring to the proposed National Council, a multiracial advisory panel that would recommend constitutional changes and include nine elected black leaders. No credible black leaders have endorsed the proposed council.

Perkins stressed, however, that a majority government would have to assure whites that their rights would be protected.

The Foreign Ministry statement, attributed only to a "senior official," declared:

"It would appear as if Ambassador Perkins is moving from his original low profile, which representatives of most countries maintain in principle with regard to domestic affairs in their host countries.

"Ambassador Perkins is, to an increasing extent, making use of public occasions to tell South Africans what he thinks of their country's policy. Relations between South Africa and the United States are sufficiently strained to make it unnecessary for Ambassador Perkins to force another point of conflict in the relations by his public statements."

The ministry statement added, "Unless American representatives preach similar moral sermons in other countries, he runs the risk that less and less attention will be paid to him."

Perkins' article, which embassy sources said was approved in advance by the State Department, did not go as far as a Sept. 29 speech by Secretary of State George P. Shultz, who called for a "democratic electoral system with multiparty participation and universal franchise for all adult South Africans."

While Shultz did not use the phrase "one-person, one-vote," constitutional experts who have explored democratic alternatives for South Africa say that any form of universal franchise, by definition, would lead to black-majority rule.

Surprisingly, Shultz's speech did not generate a protest, or even a government statement as reproachful as the one issued by the Foreign Ministry in response to Perkins' article.

One Cabinet-level official, in an interview two weeks after Shultz's speech, did not even mention his call for universal franchise, but instead complained bitterly that Shultz had credited progress in reform to pressure by antiapartheid groups and not to the government's initiative.

Following the acceptance of his credentials a year ago, Perkins made it clear that he had no intention of drawing attention to himself with public declarations about South Africa's racial policies, but instead planned to maintain behind-the-scenes contact with blacks and whites across the political spectrum, both to listen to their views and to present his government's position.

For most of his first year here, Perkins' presence was almost invisible to the public, although he made frequent unpublicized visits to black townships throughout the country and held frequent private meetings with black and white leaders.

He had no interviews or briefings with reporters, and directed embassy staffers earlier this year that all conversations with reporters should be "off-the-record" and reported immediately to his press attache.

Perkins' first public condemnation of South Africa's race policy came five months after he assumed his post, when in a brief press statement he criticized new restrictions against protesting the detention without trial of thousands of black South Africans. South Africa promptly rejected his position.

Perkins' first major policy speech in South Africa did not come until nine months after he became ambassador. Even in that speech, to a group of businessmen in Johannesburg, he did not explictly raise the sensitive issue of universal franchise, but vaguely called for a "participatory government" that would reflect the black majority.

It is mostly in the last two months, during which he has made a half-dozen public speeches, that Perkins has caught the attention of the Pretoria government.

On Nov. 12, at a university symposium at Vanderbijlpark, he called South Africa "one of the loneliest states in the modern world," and warned Pretoria that without ties to the West, "you may find yourself collapsing from internal pressures."

On Dec. 1, he drew a Foreign Ministry reproach by saying in a speech that restrictions on freedom of expression in universities had led to a "stifling of meaningful debate" throughout South Africa.

Western diplomatic sources said they doubted Perkins' recent flurry of speeches represented a decision to confront South Africa on its policies, but rather reflected a fulfillment of his intention to listen and learn before speaking out.