One-quarter of all the maize and other grain crops grown in the US now ends up as biofuel in cars rather than being used to feed people, according to new analysis which suggests that the biofuel revolution launched by former President George Bush in 2007 is impacting on world food supplies.

The 2009 figures from the US Department of Agriculture shows ethanol production rising to record levels driven by farm subsidies and laws which require vehicles to use increasing amounts of biofuels.

“The grain grown to produce fuel in the US [in 2009] was enough to feed 330 million people for one year at average world consumption levels,” said Lester Brown, the director of the Earth Policy Institute, a Washington thinktank that conducted the analysis.

Last year 107m tonnes of grain, mostly corn, was grown by US farmers to be blended with petrol. This was nearly twice as much as in 2007, when Bush challenged farmers to increase production by 500% by 2017 to save cut oil imports and reduce carbon emissions.

More than 80 new ethanol plants have been built since then, with more expected by 2015, by which time the US will need to produce a further 5bn gallons of ethanol if it is to meet its renewable fuel standard.