PRETORIA, SOUTH AFRICA, NOV. 3 -- As the South African government prepares for negotiations on a new constitution early next year with the African National Congress, authorities are formulating a plan to preserve a cornerstone of apartheid, the principle of "group rights."

Recent statements by leaders of the governing National Party have made clear their plan for a constitution that would give the impression of black majority rule, but would be hedged with enough blocking mechanisms to allow South Africa's white minority effective veto power.

"The National Party's position is . . . to strike a balance between universal franchise on the one hand and the protection of minority groups on the other," said Constitutional Affairs Minister Gerrit N. Viljoen in an interview here. Viljoen is expected to be the government's chief negotiator in talks with black leaders.

The central feature of the government's plan is a two-chamber Parliament, with a House of Representatives elected on the basis of one-person-one-vote and a Senate where "groups" and regions would have equal representation regardless of their size. As few as one-quarter or one-third of the senators would have the power to override the black majority in the lower House, vetoing or blocking a wide range of issues, a right defined in the constitution as "minority rights."

These range from guarantees of regular elections to the entrenchment of the free-enterprise system, protection against excessive taxation and the right "to live, worship, work and play with your own people" for those who wish to continue an apartheid lifestyle in segregated communities and want their children to go to their "own" schools financed by the government.

Viljoen and other government officials justify the disproportionate power that this would give to the white minority, which is one-fifth the size of the black population, by pointing to the equal representation of large and small states in the U.S. Senate.

Viljoen envisages the power of the black majority being further diluted by having what he calls a "collegiate cabinet," with ministers drawn from the various group representatives in the Senate as well as from the House.It would have to reach decisions by consensus, again giving the group representatives a veto.

Instead of having a president or prime minister, Viljoen has suggested that the chairmanship of this collegiate cabinet rotate among its members, as in Switzerland. Alternatively, Viljoen has suggested that there could be "a counterbalancing system" with executive power divided between a president and a prime minister, one from the black-majority House and the other from the group-structured Senate.

Viljoen's proposed outline for a new constitutional balance of power contradicts a statement by his own deputy, Roelf Meyer, who told a Foreign Correspondents' Association luncheon a month ago that "the days of group rights are gone." Meyer said the definition of groups based on race or color "in any form whatsoever" was unacceptable, and that attempts to define them on the basis of language or culture were impractical. Other "mechanisms" would therefore have to be found to prevent the black majority from imposing its will indiscriminately on the country's 5 million whites, Meyer said.

Viljoen was reluctant in the interview to comment directly on his deputy's remarks, which were reported in the United States and elsewhere and interpreted as a significant shift from the last remaining element of apartheid thinking by the reformist government of President Frederik W. de Klerk.

One feature of the government's plan is that it lends itself to different presentations at home and abroad, depending on where the emphasis is placed. During his foreign trips, de Klerk has emphasized his commitment to a system in which there would be one-person-one-vote elections, with each vote of equal value, mentioning -- but giving no details of -- "the protection of minorities."

He strengthened the impression of an acceptance of majority rule when he said in Holland on Oct. 22 that he would be prepared to serve under any constitutionally elected president, including ANC leader Nelson Mandela.

But at home de Klerk has sought to dispel that impression, accusing the far-right Conservative Party of spreading the "falsehood" that he believes in black majority rule. "That is untrue," he said in his keynote address to the National Party's Transvaal convention Oct. 18. "We have said clearly that we reject {black majority rule}, that it will lead to the domination of minorities. We stand for power-sharing and not for simple, typical majority rule."

In a passage redolent of old-style apartheid language, de Klerk pledged that the ruling party would build a new South Africa that would still recognize "the reality of the need for volke {peoples} and communities to remain themselves and to uphold the values that are dear to them -- so that . . . each be secure in their own distinctiveness."

Viljoen, too, laid heavy emphasis in his speeches over the past three months to the party's provincial conventions on the blocking devices and protective mechanisms he has in mind for the new constitution, sometimes using apartheid buzzwords to do so. He spoke of the need to protect the rights of individuals, minorities and "national entities," and used the Afrikaans word volksregte, meaning "people's rights" or "national rights."

The notion that South Africa was made up of different "nations," the white nation and 10 different black tribal nations, each with its own national identity that should be separated into its own national "homeland," was fundamental to the apartheid ideology of racial separation.

But Viljoen has been at pains to tell party members that the group concept must be divorced from race and based on other criteria such as culture, religion or language. He also has said membership in groups must be made voluntary.

He told the Natal provincial convention Aug. 31: "In order to market our concept of the protection of minority rights, we have to make it quite clear that discrimination has been terminated and that the protection of minority rights is not a form of introducing unequal, unfair and discriminatory treatment." It also would have to be made clear that it was not a devious way of entrenching white privileges, Viljoen said.

However, the ANC believes it is just that. Raymond Suttner, a former law lecturer at Johannesburg's Witwatersrand University who heads the ANC's Department of Political Education, says the government is trying to devise a constitution that will "create the illusion of a transfer of power but in which power will be emasculated so that the existing situation remains."