Following the collapse of preparatory talks in Bali, Indonesia, in June, agreement has yet to be reached on the summit's main goal - the drafting of a detailed plan for global economic development that preserves and protects the environment while battling hunger and poverty.

But the closed-door New York talks laid out paths toward agreement on some of the most contentious unresolved issues, the officials said, speaking on condition of anonymity.

Dutch Environment Minister Jan Pronk, who is also serving as a special U.N. envoy for summit preparations, confirmed progress was being made but declined to elaborate.

"It's better than it was in Bali. The atmosphere is better," he told Reuters.

U.N. Secretary-General Kofi Annan and South African President Thabo Mbeki called the New York talks. South Africa predicts the meeting will be the largest in U.N. history, drawing more than 100 world leaders and 60,000 delegates.

The conference is meant to build on the 1992 Rio de Janeiro Earth Summit, which set out global goals for environmental protection including a pledge to fight global warming in a deal since undermined by a U.S. pullout.

Mbeki has designated the 25 countries as "friends of the chair" in a last-ditch hunt for a final conference declaration and a concrete plan for achieving environmentally-friendly development that all 189 U.N. member-nations can agree on.

"With flexibility and mutual understanding, it should be possible for this group of 'friends' to find a common approach that can bridge the differences and produce a broad-based agreement," Annan told the group as it started deliberations.

U.N. officials say delegations have so far agreed on about 75 percent of the blueprint's text.

The parts still under negotiation touch on such fundamental issues as the setting of specific development targets and timetables for achieving them, and the question of how to pay for the programs required to achieve these goals.

The Johannesburg summit also aims to lay out a path for achieving the goals set at a U.N. Millennium summit. These include halving world poverty and hunger, achieving universal primary education and halting the spread of AIDS by 2015.

Some critics say the summit is trying to solve too many of the planet's problems at one time - an almost inevitable recipe for failure.

Others accuse the United States and other rich nations of dragging their feet on tough and potentially costly environmental and development goals.

Representatives of the Group of Eight industrialized nations Britain, Canada, France, Germany, Italy, Japan, Russia and the United States were among those attending the meeting.

Also present were Argentina, Brazil, China, Denmark, Egypt, Ghana, India, Indonesia, Jamaica, Jordan, Mexico, Nigeria, Norway, Senegal, Sweden, Uganda and Venezuela.