AFRICA : Neighbors Watching Pretoria With High Hopes, Hesitation : They have the most to gain--and lose--from an economy that could swamp theirs. The threat of a brain drain looms.

In the three weeks since President Nelson Mandela’s inauguration, a host of international organizations has rushed to embrace South Africa.

The country’s new flag flies in Addis Ababa, Ethiopia, at the headquarters of the Organization of African Unity, once one of apartheid’s bitterest enemies. On Wednesday, South Africa rejoined the British Commonwealth, more than three decades after it stormed out because of Commonwealth objections to its racist political system. And full re-integration into the United Nations is expected this year.

But as South Africa re-emerges onto the world stage, its immediate neighbors have the most to gain--and to lose. They look on with a mixture of expectation and alarm after decades of mutual hostility.

The anti-apartheid bloc known as the Frontline States Organization formally welcomes its neighbor at a meeting in Zimbabwe today, which Mandela is attending. The group does so in the hope that South Africa’s renewal will also be its own, but member countries fear being swamped by its much stronger economy. Already, the gravitational pull southward is draining some African nations of their best brains and threatening to divert international investment and aid.

In Pretoria, the Foreign Ministry’s deputy director-general for Africa, Derek Auret, says one of Mandela’s priorities in meeting with Frontline leaders will be to assess ways of establishing political and economic stability in southern Africa.

Auret says South Africa’s peaceful transfer of power to Mandela’s African National Congress might encourage a settlement of the continuing civil war in Angola and provide a reassuring example to Mozambique before it holds multi-party elections in October.

But the key to stability, he argues, will be ensuring that South Africa’s expected economic growth spills over to neighboring countries.

“Perhaps the best chance is in coming together around common economic objectives and achieving collective economic growth, which will lead to all the benefits that this government would like to see accrue to South Africans (and to) all southern Africans,” Auret said. “South Africa cannot be an island of prosperity in a sea of poverty.”

But Pretoria is keen to discourage exaggerated expectations. “South Africa’s potential is a long-term issue,” Auret said, “and won’t have any immediate spinoffs for the rest of the continent.”

Some of South Africa’s new leaders do feel a deep emotional debt to nations such as Zambia, Zimbabwe and Tanzania because they helped hold the line against apartheid over the years. They also recognize that assisting their neighbors eventually will conflict with their own government’s interests and priorities.

Mandela needs rapid economic expansion if he is to provide jobs and housing to his constituents, yet South Africa’s economy is already three times larger than the economies of the seven Frontline states combined. It exports five times as much to the continent as it imports.

Economists point out that further expansion will likely widen the financial gap between South Africa and its neighbors. Among the few African exports into South Africa today are professionals--doctors from Ghana and Zaire, managers from Nigeria, teachers from Zimbabwe. While South Africa welcomes them, the other nations despair at the loss.

And domestic pressure is building on Mandela to stem the flow of unskilled migrant labor from Zimbabwe, Mozambique, Malawi and Lesotho--a vital source of revenue for those nations. There are estimated to be at least 2 million illegal immigrants in South Africa holding jobs the ANC urgently needs to provide to its own citizens.

Other African nations also fear Pretoria will garner a sizable chunk of what little foreign investment and Western aid the continent gets.