High oil prices, the need for secure energy supplies, and worries about climate change are all increasing interest in bio-fuels, including wood.

But Tuesday's FAO report cautions that growing demand for the world's most important bio-fuel might also lead to deforestation and other problems if not managed in a sustainable way.

The FAO says using more wood for fires, or as a source of liquid bio-fuels, could raise the price of wood for other uses. Wood is already the dominant source of energy for about two billion of the world's people, particularly in developing nations. - VOA News