Talks on Reshaping S. Africa to Start : Apartheid: Black and white leaders agree to open constitutional negotiations Dec. 20. The process may last a year or more.

Taking the first step toward ending decades of white rule in South Africa, black and white leaders met behind closed doors Friday and formally agreed to open constitutional talks in three weeks.

The talks, to be called the Convention for a Democratic South Africa, were set for Dec. 20 and 21 at the World Trade Center in Johannesburg.

The decision, reached by delegates from 22 political organizations sitting around a horseshoe-shaped table, marked the beginning of what will probably be a tedious process designed to grant voting rights for the first time to that country’s black majority. The negotiations will probably run through most of 1992 and perhaps into 1993.

“We see it as a victory for the people of South Africa that we have finally arrived at the point at which the process, which will lead to a democratic dispensation, has been triggered,” said Cyril Ramaphosa, secretary general of the African National Congress, the leading black opposition group.

“We are very optimistic,” he added. “The process is really kicking off in a positive way.”

Roelof Meyer, the government defense minister who represented the ruling National Party, said, “There’s no alternative to negotiations.”

His Cabinet colleague, Constitutional Affairs Minister Gerrit Viljoen, described the meeting as “a watershed on the road to a democratic constitution” but warned that long and difficult negotiations remain.

Most of the major political groups in South Africa were represented at the meeting, which opened at a Johannesburg hotel with backslapping, handshakes and broad smiles. The government and President Frederik W. de Klerk’s National Party sent separate delegations, and the delegates agreed that government representatives will have no vote once formal negotiations begin. The ANC’s close ally, the South African Communist Party, also sent a separate delegation that included ANC office holders.

None of the country’s top political leaders--De Klerk, ANC President Nelson Mandela or Inkatha Freedom Party leader Mangosuthu Gatsha Buthelezi--was present for the planning session, which resumes today.

The delegates first elected Superior Court Judges Ismail Mahomed and Petrus Schabort as co-chairmen of the Friday talks, which then settled on an agenda for the coming negotiations. Among the matters on that agenda will be general constitutional principles, on which most of South Africa’s political leaders agree, and the process for drawing up that constitution, on which there is substantial disagreement.

The ANC, the left-wing Pan-Africanist Congress and most other black groups want the constitution written by a “constituent assembly” elected in a one-person, one-vote national election.

De Klerk’s National Party and Buthelezi’s Zulu-based Inkatha Freedom Party oppose that method, which would probably give the ANC a strong say in drafting the new constitution. They prefer to write the constitution during negotiations and then put the result to a national vote.

The Convention for a Democratic South Africa also will discuss transitional arrangements, such as an interim government or power-sharing, during the negotiation period. And the delegates agreed that the convention will consider the future of the nominally independent black homelands as well as the role of the international community in the constitution-making process.

The planning session agreed to invite all 22 groups involved in Friday’s meeting, as well as those parties that have so far refused to enter talks on the country’s future. Among those are the Azanian People’s Organization, a militant left-wing group, and the right-wing white Conservative Party, which represents about 25% of the white electorate. The Conservatives’ participation is considered a key to the success of any negotiations.

On Thursday, in a mining constituency in the Orange Free State, the Conservatives scored an impressive, though expected, victory in a by-election to fill a vacant parliamentary seat that had been held by the National Party.

But the Conservatives are sharply divided over whether to participate in constitutional negotiations. And if formal talks get under way next month as planned, support for De Klerk’s reform process among whites is likely to grow, giving the president a strong hand when the new session of Parliament opens Jan. 24.

Most decisions at the meeting Friday were taken by unanimous vote or “by sufficient consensus where necessary,” according to a statement issued by the session chairmen. But the meeting highlighted growing differences between the ANC and the smaller, more radical Pan-Africanist Congress. Recent public sniping by the ANC and the PAC has all but destroyed the much-heralded “patriotic front” alliance reached by the two groups last month.

The ANC and PAC had reached broad agreement on the need for a constituent assembly and an interim government, but the ANC appears to be more willing to compromise. That flexibility, and the groups’ traditional rivalry--both conducted 30-year guerrilla wars against the white-minority government--has put them at odds.

Although the PAC agreed to participate in the negotiations next month, most of its proposals were thwarted by the delegates. And Barney Desai, leader of its delegation, complained at a news conference that the ANC had sided with the government and black homeland leaders on virtually every matter up for discussion Friday.

Earlier in the week, the PAC accused the ANC of making secret pre-negotiation agreements with the government, a charge that both the ANC and the government strongly denied.

The PAC tried to open Friday’s meeting to the news media, but that proposal was voted down by other delegates. PAC leaders also were thwarted in their attempt to have the negotiations next month held outside the country, under the direction of representatives of a neutral body such as the Organization of African Unity or the United Nations.

But delegates agreed that the venue and chairmanship of future negotiations will be up for discussion at the December sessions. Representatives of the OAU, the United Nations and heads of diplomatic missions, including U.S. Ambassador William Lacy Swing, will be invited as observers.