The EU, struggling to reduce its dependence on foreign energy sources, aims for biofuels to make up a 5.75 percent share of transport fuels by 2010. But the goal is voluntary for EU member states and looks set to be missed.

"We need to stimulate the demand for biofuels," said EU Agriculture Commissioner Mariann Fischer Boel, adding that the EU executive would publish a report on a possible revision of the bloc's biofuel rules later this year.

She told a news conference that she was "quite sure" there would be a discussion on whether to make targets mandatory and whether to increase the 5.75 percent goal. But she declined to say whether she herself would push for such a move.

The Commission published a strategy paper on Wednesday, which proposed ways to promote biofuels in the EU and developing nations, make the fuels more competitive in terms of costs, and boost research into "second generation" biofuels.

"Increased use of biofuels will bring numerous benefits, by reducing Europe's dependence on fossil fuel imports, reducing greenhouse gas emissions, providing new outlets for farmers and opening up new economic possibilities in several developing nations," the Commission said in a statement.

The EU produced 2.4 million tonnes of biofuels in 2004, including 0.5 million tonnes of bioethanol and 1.9 million tonnes of biodiesel.

Though burning biofuels releases emissions into the atmosphere, such pollution is considered less destructive than fossil fuels because the crops in biofuels essentially breathe in carbon dioxide (CO2) when they grow, making the re-release of CO2 neutral in terms of environmental impact.

But environmentalists warn that the use of pesticides, fertilisers and the fuels needed to transport the crops themselves add to the environmental risk.

Environmental group WWF called for an "eco-certification" to ensure biofuels did more good than bad.

"It is imperative that the EU establishes a legally binding certification system for both imported and domestic biofuels," said Elizabeth Guttenstein, Head of European Agriculture and Rural Development at WWF, in a statement.

"The certification system must be based on enhancing the potential of biofuels to cut greenhouse gas emissions, while avoiding the wider environmental impacts of biofuel production."