Genetically-modified crops are among measures needed to tackle problems with global food supplies that could see prices soar, leading scientists said today.
A new Government-commissioned report warned that there were major failings in the global food system that damages the environment and leaves one billion people hungry.
A further one billion suffer from "hidden hunger" in which nutrients are missing from their diet and the same number are over-consuming, while a third of all food produced is currently wasted.
Without action to tackle the problems with agriculture and production, the pressure on food supplies will increase in the face of a rising world population, competition for land, water and energy and the effects of climate change.
While it is hard to predict the impact on food prices, there is a risk of the kind of volatility seen in the price spike in 2007/08 that led to riots in some parts of the world and an extra 100 million people going hungry.
Experts behind the report suggested that food prices could rise by 50% by 2050.
Government chief scientist Professor Sir John Beddington said: "There's a very large risk of quite a substantial increase in food prices in the next 30 to 40 years.
"This risk is such it demands urgent action on all components of the food system - supply, demand and making the food system work more efficiently."
The current food system was "fundamentally unsustainable", over-using resources such as land and fossil fuels while failing to feed the world, he said.
He said the report calls for "sustainable intensification" of agriculture to produce more food from the land available - as there was no new land to be brought into production - without harming the environment.
He said biotechnology, such as genetically modified crops, is "extremely important" and that the report shows no option should be closed off.
But it was just one of a number of measures needed, along with steps including improving farmers' skills and investing in scientific knowledge and infrastructure such as roads.
The report found that a third of food produced went to waste, either after it was harvested, particularly in the developing world, or by consumers.
In the UK, households could save between £500 and £700 a year by eliminating food waste.
Professor Jules Pretty, of the University of Essex, said measures ranging from conservation farming to biogas digesters to make energy and fertiliser from animal waste were already being used.
He said that - following the "green revolution" which massively boosted agricultural production in the 20th century - there needed to be the "greenest revolution" to improve agriculture without harming nature.
"Both organic methods and GM are going to be important. We need to get beyond these binary options," he said, calling for a "both/and" approach to farming methods rather than an "either/or".
Environment Secretary Caroline Spelman said there was a need for a global approach to food security that also tackled poverty and climate change and reduced losses to wildlife and environmental damage.
"We can unlock an agricultural revolution in the developing world, which would benefit the poorest the most, simply by improving access to knowledge and technology, creating better access to markets and investing in infrastructure.
"To fuel this revolution, we must open up global markets, boost global trade and make reforms that help the poorest.
"Trade restrictions must be avoided, especially at times of scarcity.
"And we must manage price volatility by building trust and cooperation - and in particular by creating greater transparency around the true levels of food stocks," she said.
Asked if she saw an end to the EU policy of agricultural subsidies, she said that while the Government could see a time coming when subsidies would not be needed, they were still necessary but should be used to support environmental benefits of land management as well as producing food at reasonable prices.
Professor Lawrence Haddad, director of the Institute of Development Studies, said action should prioritise the needs of women farmers, who made up the majority of producers in the developing world but were systematically excluded from access to resources and knowledge.
International Development Secretary Andrew Mitchell said: "This report makes very clear the implications of a population increase to nine billion people by 2050 - two billion more hungry mouths to feed, less land available to feed them from, higher rates of malnutrition, and increasing food price volatility that will hit the world's poor hardest.
"As the report shows, the right technology and research findings already exist to help to increase yields, reduce waste throughout the production process, and tackle the diseases or difficult conditions that can limit livestock and crop production.
"What we must do now is ensure that those who would benefit most from these solutions are better informed of their existence and have the chance to put them to practical use."
Dr Julian Little, chairman of biotech industry body ABC, said: "As population and resource pressures increase, the challenge of ensuring a secure and sustainable global food supply system grows ever more pressing.
"Already, over 300 million acres of land are planted each year with GM crops and over 2 trillion meals containing GM ingredients have been consumed with no adverse health effects.
"As the report recognises, GM technology is not a silver bullet that will solve all of the challenges we face on its own, however it is an essential tool in the armoury, and further research and development may herald further advances in dealing with the challenge of demand growth and climate change."
But the World Development Movement's director, Deborah Doane, said current record food prices were down to banks and hedge funds betting on food - and that GM was not a magic bullet to cure global hunger.
"The hot speculative inflows of money into commodity markets are dramatically pushing up the price of foods like bread, sugar and corn."
"If the UK Government really wants to reduce hunger in the developing world, they should break free of the grip of the GM and banking lobbyists and crack down on predatory speculation by banks and hedge funds which will ensure stable and lower food prices.
"Furthermore, the UK Government should be focused on supporting strengthening local markets and investing properly in smallscale farmers in developing countries."
Commenting on the report, Professor Tim Lang, of the centre for food policy at City University London, said: "While the focus is often on Africa, the reality is that the Western world's model of food production and consumption is not sustainable either.
"We over-consume, pay too little, have heavy environmental footprints, and distort our health.
"Yet somehow the politicians and policymakers won't get a grip. They are frightened of unlocking us from an unsustainable system which celebrates cheap food by damaging people and the planet."
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