"We are starting a world campaign to ban all inefficient lightbulbs," Barbut said at the Reuters Environmental Summit in Washington. "And China has just agreed."

China's program will be formally announced in December at a meeting of climate negotiators in Bali, Indonesia, she said.

The switch to more efficient bulbs from traditional incandescent ones could mitigate 500 million tonnes of the greenhouse gas carbon dioxide annually, equal to about half the climate-warming emissions of Germany, she said.

China is the first developing country to agree to join this program, and the facility will invest about US$25 million for the Chinese program alone.

Other countries -- including Mexico, Indonesia, Venezuela and Costa Rica -- may join in future, Barbut said.

"If we decide and if countries really agree, it is something that could be done in the next 10 years," she said.

ENERGY EFFICIENCY FOR THE POOR

The Global Environment Facility is one of the richest and least-known environmental funding agencies worldwide.

With a current trust fund of about US$3.2 billion, the Washington, D.C.-based agency is the financial arm for international intergovernmental agreements on biodiversity, climate change and persistent organic pollutants. It also supports agreements on international waters, ozone and desertification.

As the lightbulb switching program goes forward, the environment facility is working to develop a fund to get these more efficient bulbs into the hands of the poor

"An efficient lightbulb costs four times more than an inefficient lightbulb -- it lasts 10 times longer but it's four times more (expensive) -- and for many very poor people ... the problem is that they can't afford the four times more at one time," Barbut said.

Compact fluorescent lamps use between a quarter and a fifth of the energy of incandescent bulbs producing the same light.

Among rich countries, Australia has already decided to phase out incandescents by 2010, Barbut said, and the facility is working with the Australian government to help with the China project.

The matter is being discussed by countries in the European Union and the United States, she said, adding that China is ahead of the United States in this respect.

The backing of the Global Environment Facility is likely to produce an international market benefit, according to Barbut.

Because the program will be worldwide, it could reduce the number of types of lightbulbs from 30 or so to four or five, thus reducing the cost of manufacturing equipment.