In Indonesia, he said, more than 18 million hectares of forest, or 44 million acres, have already been cleared for palm oil developments. Environmental groups say the developments are endangering wildlife like the orangutan and the Sumatran tiger, and putting pressure on indigenous peoples who depend on the forests.

Western scientists are increasingly pointing out the need to distinguish between types of biofuels. On Monday, for instance, the Royal Society, a national science academy in Britain, said requirements to use a certain percentage of biofuels were not sufficient. Instead, the society said, there should be specific goals for emissions reductions.

“Indiscriminately increasing the amount of biofuels we are using may not automatically lead to the best reductions in emissions,” said John Pickett, head of biological chemistry at Rothamsted Research, a research center in Britain, who helped write the report for the Royal Society. “The greenhouse gas savings of each depends on how crops are grown and converted and how the fuel is used.”

Last week, scientists at the Smithsonian Tropical Research Institute in Washington also warned that biofuel production can result in environmental destruction, pollution and damage to human health.

“Different biofuels vary enormously in how eco-friendly they are,” said William Laurance, a staff scientist at the institute. “We need to be smart and promote the right biofuels.”

Experts say certain types of fuels, particularly those made from agricultural wastes, still hold potential to improve the environment, but they add that governments will have to set and enforce standards for how the fuels are produced. With its new proposal, Europe appears to be moving ahead of the rest of the world in that task.

The draft law probably would have the greatest impact on palm oil growers in countries like Malaysia and Indonesia, according to Mr. Drinkwater.