'Modern agriculture will have to change radically to better serve the poor and hungry if the world is to cope with a growing population and climate change, while avoiding social breakdown and environmental collapse,' the 400 experts behind the report said.

Broadly speaking, they said the blinkered efforts of governments and industry to simply raise production should be abandoned in favour of a greater focus on producing food in an eco-friendly way and distributing it more equally.

The International Assessment of Agricultural Science and Technology for Development (IAASTD) report said current farming methods already produce enough to feed the world.

But it also said that, together with the way food is traded, they still leave more than 800 million people hungry.

The New York Times quoted the report as saying that such methods come at 'an increasingly intolerable price, paid by small-scale farmers, workers, rural communities and the environment'.

IAASTD director Robert Watson was quoted by Britain's Guardian newspaper as saying: 'Business as usual will hurt the poor. It will not work.'

Instead, the report's authors said there should be more research into ways to protect soils, water and forests, with less reliance on fossil fuels and greater use of locally available resources and natural fertilisers.

The four-year study, commissioned by the United Nations and World Bank, is backed by countries such as Brazil, China, France and India. The United States, Australia and Canada are due to submit reservations.

It also comes amid soaring food prices, which have triggered violent protests globally, and takes aim at genetically modified (GM) crops and biofuels.

While not ruling out the possible benefits of GM food, the scientists said that much of the evidence of its benefits was anecdotal and contradictory.

'The short answer to whether transgenic crops can feed the world is 'no',' said Professor Watson.

The report also said biofuel production is unsustainable.

It added: 'Diversion of crops to fuel can raise food prices and reduce our ability to alleviate hunger.'

Summing up the report's findings, Prof Watson was quoted by the Guardian as saying: 'Continuing with current trends would mean the earth's haves and have-nots splitting further apart. It would leave us facing a world nobody would want to inhabit.'