Johannesburg, South Africa ? The United States, Saudi Arabia and other wealthy nations at a U.N. summit worked Tuesday to water down proposals to rapidly expand the use of clean, renewable energy technologies around the globe.

Renewable energy sources like wind power and solar energy produce smaller and more expensive amounts of electricity than a traditional power plant. But the technologies generate a tiny fraction of the smog that comes from burning oil, coal and other fossil fuels, as well as carbon dioxide and other gases believed to accelerate global warming.

A proposal for the World Summit on Sustainable Development’s action plan calls for the use of the technologies to be increased to account for 15 percent of the world’s total energy production by 2010.

Sources sitting in on the negotiations said delegates from the United States, Saudi Arabia and other industrialized and oil states were lobbying to eliminate the provision and set no specific goals.

Even the European Union some members of which, like Germany, strongly embrace renewable energy sources wavered on the agreement.

The moves by the industrialized countries angered environmental groups, which are demanding stiffer anti-pollution measures.

The 10-day summit, which began Monday, is focused on uplifting the world’s poor and protecting the global environment. The United Nations expects it to be the largest summit in its history. More than 100 heads of state are scheduled to attend.

During Tuesday’s open session, delegates called for increased global efforts to bring new agricultural technologies to poor farmers and railed against European and American agricultural subsidies, saying they made it difficult for poor farmers to compete on the world market.

Developing countries are hoping the summit’s action plan will call for the reduction or elimination of subsidies, a provision opposed by wealthy countries. The summit was unlikely to resolve the issue. “No country can realistically be expected to make a major commitment here on those matters,” South African Trade Minister Alec Erwin said.

Targets and timetables were added to the summit’s implementation plan as organizers sought new ways to compel nations to live up to their pledges made in the heat of international diplomacy. In the 10 years since the Earth Summit in Rio de Janeiro, treaties protecting biodiversity and limiting climate change have languished.

However, the United States is seeking to erase specific targets and timetables on many topics throughout the plan, which includes 150 pages addressing biodiversity, food security, clean water and health care.

Instead, U.S. officials said they preferred voluntary partnerships with business and other groups.