UNITED NATIONS -- Production of environmentally friendly goods is set to double, with turnover of $2.7 billion a year by 2020, a report released Wednesday at the United Nations said.

"We are not talking about niche markets anymore. We are talking about millions of jobs that are emerging across the global economy," said Achim Steiner, UN Environment Program executive director.

"It is the entrepreneurial world, because of what is happening in terms of the natural resources markets on the global market place, that is pushing for this," he told journalists at the UN General Assembly in New York.

The program's report on the green industry said that 2.3 million people are employed in the renewable energy sector alone -- half of them in developing countries. About 2.1 million could be working in wind energy and 6.3 million in solar energy by 2030, the report said.

Already the renewable energy industry employs more people than the fossil fuels sector, according to the report.

"The transition has already started," said Juan Somavia, director general of the International Labour Organization.

"In Germany renewable the energy sector will be larger that automobile and machine manufacturing in the next ten years. In France energy efficiency and renewable energy already employs more than the car industry," he said.

But Somavia also cautioned: "We need to make sure that green jobs are decent jobs. Millions of workers are involved in recycling discarded computers and mobile phones, but they are often in bad quality jobs: the first thing that goes to the recycle bin are safety and healthy rules."