Britain and Europe will be forced to fundamentally rethink a central part of their environment strategy after a government report found that the rush to develop biofuels has played a "significant" role in the dramatic rise in global food prices, which has left 100 million more people without enough to eat.

The Gallagher report, due to be published next week, will trigger a review of British and EU targets for the use of plant-derived fuels in place of petrol and diesel, the Guardian has learned.

The study marks a dramatic reversal in the role of biofuels in the fight against global warming. As recently as last year, corn ethanol and biodiesel derived from vegetable oil were widely seen as important weapons in that fight - and a central plank of Gordon Brown's green strategy. Now even their environmental benefits are in question.