A furious attack on the drive to grow more biofuels has been launched by a charity supporting poor farmers in developing countries.
The charity - called Grain - says their research shows the rush for biofuels is causing much more environmental and social damage than previously realised.
Biofuels from crops are being heavily promoted by the US and Europe as a welcome solution to climate change.
In theory their emissions are much lower than from fossil fuels.
But the report from the charity Grain amplifies recent warnings from the UN's Food and Agriculture Organization (FAO) that some biofuels produce hardly any carbon savings at all.
The UN says basic food prices for poor countries are being pushed up by competition for land from biofuels.
The Grain report says its research shows show that governments and biofuels firms in developing countries are collaborating to push hundreds of thousands of indigenous people and peasant communities off their land.
Grain says: "The numbers involved are mind-boggling. The Indian government is talking of planting 14 million hectares of land with jatropha.
"The Inter-American Development Bank says that Brazil has 120 million hectares that could be cultivated with agrofuel crops; and an agrofuel lobby is speaking of 379 million hectares being available in 15 African countries. We are talking about expropriation on an unprecedented scale."
It points out that one of the main causes of global warming is agro-industrial farming itself, thanks mainly the use of chemical fertilisers which introduce nitrous oxide into the air.
The group says the media has been spun into using the attractive term biofuels - and wants them referred to as "agro-fuels" instead.
The plant fuel industry accepts that there is a limit to the energy to be obtained from crops - but believes plant fuels can be produced sustainably on a large scale. The EU wants to see at least 10% of road fuel derived from plants by 2020.
Oil firms believe this target is achievable using farm surpluses combined with fuel digested by bacteria from waste - so called second generation biofuels.
But their economic calculations do not include competition for feedstock from power firms wanting biofuel for combined heat and power - which produces much more energy more economically than liquid fuel.
This may be pretty dangerous for the farmers and poor families.