Delegates crowded the plush Sandton convention center, just a short walk from some of Africa's most squalid slums. Inside, idealistic campaigners showed off the benefits of solar cooking stoves while outside the South African armed forces put on an impressive display of hardware to discourage violent protests.
Mbeki, who said on Sunday that "global apartheid" must go the same way as white minority rule in South Africa, criticized the failure of governments to act on pledges made 10 years ago in Rio de Janeiro to pursue environmentally friendly prosperity.
But after preparatory talks at the weekend, negotiators still face an uphill struggle over the next 10 days to narrow a gulf between poor nations seeking more aid and fairer trade and wealthy powers led by the United States and European Union, who want to see better government in the Third World in return.
One focus for dispute could be Robert Mugabe, president of neighboring Zimbabwe and a target of bitter Western criticism over human rights abuses and seizures of white-owned farmland.
World leaders are due in Johannesburg next week, hoping to sign a broad "implementation plan" that the UN organizers hope will revive the spirit of Rio on a wide range of issues, from improving healthcare to saving rainforests and fish stocks.
"This is not a conference to solve every single problem. But this is a test -- we have to come out with credible commitments for action," the summit's UN organizer Nitin Desai said.
But critics point out that, as in Rio, the texts under discussion are vague and not legally binding. President Bush does not even plan to attend, prompting fury among critics already dismayed by his rejection last year of the Kyoto accord to cut the air pollution blamed for global warming.
There has been little sign of the sort of mass street protests that have marred international meetings in Seattle, Genoa and elsewhere. But Johannesburg police, still shaking off an apartheid-era reputation for brutality, are taking no chances, clamping down hard on small protests. Anger is brewing among environmental campaigners at what they perceive as a drive by Americans and Europeans to push the demands of globalized big business above those of the very poor.
"There is a possibility the two worlds will never touch," Paul Mayer of the Tribal Link Foundation said after a visit to the Alexandra shanty town, overlooking the Sandton summit venue.
"When we make foreign policy we should always have children in mind and I always fear those people in their thousand-dollar suits, staying in their luxury hotels, don't do that."
The United Nations was expected to release on Monday a list of partnerships between governments and private enterprise that have won its approval for helping the poor and the environment.
Washington is a strong advocate of such initiatives, but critics say they are a way of evading state responsibilities.
A DOLLAR A DAY
Developing nations say already agreed U.N. goals that should form part of the Johannesburg plan require more Western aid if they are to be met and also want to see new commitments from the rich states to open up their markets to Third World produce.
A key goal is to halve the proportion of the population -- at present 1.2 billion people -- living on less than a dollar a day compared to an average in Europe of about 60 times that.
Subsidies to American and European farmers already account for several times the total global annual aid budget of $54 billion and mean farmers in developing nations cannot compete.
But Western negotiators are resisting efforts to reopen negotiations on aid and trade that have already been concluded in separate meetings, at Monterrey and Doha, in the past year.
A senior member of the U.S. delegation, to be headed by Secretary of State Colin Powell, urged developing countries to be realistic in "tough negotiations." He said: "We just can't let ourselves get trapped and mired in some of these issues."
European Union officials said they were open to some of the poor states' demands for more concrete targets but were reluctant to push ahead without the United States.
"We're willing to be held accountable but we want our partners to join us," said Catherine Day, a senior EU official.
The summit will concentrate the work of its thousands of official delegates on five key areas -- cleaner water, non-polluting energy, better health, sustainable agriculture and preserving the "biodiversity" of the Earth's many species.
The UN's Desai highlighted links between all the issues. Educating women pulled communities out of poverty, he said. And a good way to do that in many arid regions of Africa and Asia was to provide fresh water, sparing girls long walks to wells.
Healthcare was on the agenda on Monday. One South African in nine suffers from
HIV/AIDS, which has decimated Africa's workforce and left millions of children