Nathalie Kosciusko-Morizet said the government had asked the French agency for environment and energy ADEME to review the technology with a focus on the second generation of biofuels, mostly made of plant waste instead of grains and vegetable oils.

"France's policy on this matter is empowered to be reshaped after ADEME's report," she said at a briefing organized by the European American press club in Paris.

France has become one of the largest producers of biofuels in Europe after it set an ambitious policy that anticipates by two years the EU target on the blending of biofuels with standard fuels.

To reach its incorporation objectives -- 7 percent of all fuels by 2010, and 10 percent by 2015 -- France put in place a system of quotas benefiting from reduced taxes in a bid to make them competitive compared to standard fuels.

The policy prompted many companies to invest in the sector, building ethanol and biodiesel plants across the country.

But concern has since risen on whether biofuels -- once hailed as a way of reducing the world's reliance on crude oil and slowing climate change -- really help cut greenhouse gas emissions and or if they may contribute to rising food prices.