UK's chief environmental scientist has warned that an increased reliance on biofuels could lead to an increase in greenhouse gas emissions.
According to a report in The Scotsman, the scientist in question is Professor Robert Watson, who gave the warning just days before Westminster is to introduce a policy dictating minimum levels of the fuels at the pumps.
Watson said that it would ''obviously be totally insane'' to have a scheme aimed at reducing greenhouse gases by using biofuels, which instead led to an increase in emissions.
Biofuels, mainly ethanol and diesel made from plants, have been promoted as an alternative to the use of conventional fuels in transport, which account for about a quarter of global greenhouse emissions.
Their proponents say they are a sustainable solution to global warming. Crops such as palm oil, corn and sugar cane are grown as normal and processed for their energy.
They absorb carbon dioxide as they grow, meaning in principle fuels such as bioethanol and biodiesel should have lower overall emissions than fossil fuels such as oil or coal.
But, according to Professor Watson, chief scientist at the Department for the Environment, the environmental sustainability of the biofuels needed verification.
''I think it's now indeed clear that while some sources of biofuels do appear to be potentially sustainable from an environmental point of view, others certainly are not,'' he said.
''Biofuels threaten untold damage to unique wildlife habitats across the world,'' said Abigail Bunker, agriculture policy officer of the RSPB.
''Their production is already causing the destruction of rainforest, peatlands and grasslands and the release of huge amounts of carbon stored by trees and soil,'' he added.
While biofuels may be billed as environmentally preferable to fossil fuels, some experts admit they bring their own problems. These include: deforestation, which will lead to increased carbon emissions and loss of biodiversity; loss of land for food crops, which could send prices higher; and, environmental damage from lorries transporting the fuels.