World governments sat down together in Johannesburg on Saturday for negotiations that could well decide whether next week's mammoth Earth Summit ends in new global harmony or ugly recriminations between rich and poor. Ten years after a first grand conference in Rio de Janeiro, many of its promises to narrow the yawning wealth gap without the environmental damage that has accompanied prosperity in the West have either been broken or, at best, remain unfulfilled.

Angry protesters are expected to drive home that point to world leaders at the gleaming Sandton Convention Center, a stone's throw from some of Africa's most squalid slums.

Well before Monday's formal opening of the 10-day summit, police were out in force and even U.N. staff running the event, as well as accredited journalists, had trouble getting through.

There was already trouble beyond Johannesburg -- Greenpeace said up to a dozen activists were detained during a protest at Africa's only nuclear power station near Cape Town.

After deadlock in preparatory talks for the Johannesburg summit, senior officials hope to narrow differences over the weekend between developing countries seeking more aid and open trade and wealthy nations setting tough conditions on those.

U.S. ACCUSED OF RELUCTANCE TO GRANT DEVELOPING COUNTRIES ACCESS TO ITS MARKETS

The aim is to agree a broad -- though vague and not legally binding -- plan to ease poverty while at the same time ensuring that greater prosperity for a burgeoning world population does not bring with it the environmental damage caused in the West.

Up to a third of a 77-page draft agreement dealing with issues from development aid and water purification to saving rainforests and fighting AIDS remains in dispute, officials say.

If negotiations do produce a document that world leaders can sign off on when they show up for the summit finale, they will mostly be doing little more than reiterate commitments made previously. But the United Nations organizers hope nonetheless that the process can revive Rio's green agenda for the planet.

Talks in Bali in June broke down with many delegates from developing nations accusing the United States in particular of reluctance to grant more aid and access to its markets for their goods.

POWELL DEPUTIZES FOR BUSH

President Bush has said he will not join 100-odd other leaders at the end of the World Summit on Sustainable Development and has angered many environmental lobbyists by pulling out of the Kyoto pact that sets targets for cutting the pollution blamed for global warming.

While supporting the overall goals of alleviating poverty and preserving the health of the planet, Washington is deeply suspicious of fixing firm targets for performance that it fears could hurt the economy and be cheated on by other states.

It has also made clear it will not go along with attempts to open up new negotiations in Johannesburg on aid budgets and trade following deals cut in other, separate forums. Secretary of State Colin Powell will represent Bush in South Africa.

PHOTO CAPTION

A billboard on a Johannesburg highway August 23, 2002, displays the names of some of the heads of state expected in South Africa for the Earth Summit next week. Government experts will try this weekend to salvage next week's Johannesburg Earth Summit from a North-South rift that threatens to block a planned blueprint for halving poverty while protecting the environment. (Juda Ngwenya/Reuters)