LONDON - Most biofuels harm rather than help the environment and the government should call a moratorium on increasing their use, a parliamentary committee said on Monday.

"Biofuels can reduce greenhouse gas emissions from road transport - but at present most biofuels have a detrimental impact on the environment overall," Tim Yeo, chairman of the House of Commons Environmental Audit Committee (EAC) said.

Biofuels can be substituted for fossil fuels and are seen by advocates as a way of reducing emissions of greenhouse gases believed to contribute to global warming. Grains, vegetable oils and sugar are among the industry's current feedstocks.

Britain has ordered transport fuel suppliers to supply five percent of their UK road fuel from renewable fuels by 2010.

The Royal Society, the national academy of science, issued a report last week saying the government directive would do little to combat climate change because it lacked targets to reduce greenhouse gas emissions.

"There are many different types of biofuels and it's key that the ones we use provide the best greenhouse gas savings and are produced in ways that are good for people and the environment," Dianna Bowles of the Royal Society's biofuels working group said in response to the EAC report.

The EAC report said a large biofuel industry based on current technology is likely to increase food prices and could damage food security in developing countries.

Research is under way to develop so-called second generation biofuels which would use waste products rather than food commodities. The committee noted that these technologies are some years away.

Britain's National Farmers Union rejected the conclusions.

"Biofuels represent the only renewable alternative for replacing fossil fuel in transport and a way of tackling one quarter of UK carbon emissions which transport is responsible for," NFU president Peter Kendall said in a statement.

"UK biodiesel reduces greenhouse gas emissions by 53 percent and UK wheat bioethanol by 64 percent compared with their fossil fuel equivalents.

"Those savings can and should be improved. But for the committee to conclude that, because the savings are small, they are not worth having at all, is illogical and ill-informed," Kendall added.