Prices of staple foods will more than double over the next two decades unless urgent action is taken to change the rules of world agriculture, Oxfam has warned, raising fears that hundreds of millions more could face hunger.

Youths hold posters during a march against hunger in Tegucigalpa May 29, 2011. “Depleting natural resources, a scramble for fertile land and water, and the gathering pace of climate change is already making the situation worse,” Oxfam said, in a report titled Growing a Better Future. (REUTERS/Edgard Garrido) Maize, one of the main foods of the world’s poor, will cost between 120 per cent and 180 per cent more by 2030, with up to half of the price hike coming from the impact of climate change, said the London-based charity.

“Depleting natural resources, a scramble for fertile land and water, and the gathering pace of climate change is already making the situation worse,” it said, in a report titled Growing a Better Future. The dangers, caused by demand outstripping production, threaten to erase much of the “steady progress in the fight against hunger” made over recent decades, said Oxfam.

Illustrating the international inequalities, it pointed out that in the Philippines, people spend four times as much of their income on food as people in the UK, while the average Indian spends twice the UK average. “As a proportion of their income, Indian people pay the equivalent of £10 for a litre of milk and £6 for a kilo of rice,” said the charity, which tomorrow launches a campaign calling for reform of global agriculture rules.

By 2050 demand for food will rise by 70 per cent, yet our capacity to increase production is declining and the increase in yields has almost halved since 1990, it says.

Despite the increased use of chemicals and genetically modified crops, the increase in yields “is set to decline to a fraction of 1 per cent in the next decade”.

“Eight million people, the majority of them women and girls, currently face chronic food shortages in east Africa. Increasing numbers of regional and local crises could see the need for food aid double in the next 10 years,” Oxfam went on.

The Grow campaign, launched today in 45 countries, is backed by former Brazilian president Luiz Inácio Lula da Silva and Archbishop Desmond Tutu.

Oxfam criticised the United States and the European Union for promoting biofuels, saying the policy ensures that “15 per cent of the world’s maize is used to make fuel, even at times of severe food crisis.

“The amount of grain required to fill the petrol tank of a 4x4 vehicle with biofuel is sufficient to feed one person for a year. Meanwhile, EU targets in practice mean that 10 per cent of transport fuel will be biofuels by 2020.”

Meanwhile, the number of Indians suffering hunger between 1990 and 2005 increased by 65 million – “more than the population of France” – because economic development excluded the rural poor, and welfare programmes failed to reach them.”

Five hundred million farmers, many of them women in poor countries offer “the single biggest opportunity to boost food production”, but they must be helped to protect themselves from the impacts of climate change and better equipped to produce food.

Archbishop Tutu said: “Many governments and companies will be resistant to change through habit, ideology or the pursuit of profit. It is up to us – you and me – to persuade them by choosing food that’s produced fairly and sustainably.”