International development NGO Oxfam has warned of a ‘‘broken system’’ where obesity and starvation are two sides of the same coin.

Rising prices are tightening the squeeze on populations already struggling to buy adequate food, demanding radical reform of the global food system, Oxfam has warned. By 2030, the average cost of key crops could increase by between 120% and 180%, the charity forecasts.Half of the rise to come will be caused by climate change, Oxfam predicts. It calls on world leaders to improve regulation of food markets and invest in a global climate fund.

‘‘The food system must be overhauled if we are to overcome the increasingly pressing challenges of climate change, spiralling food prices and the scarcity of land, water and energy,’’ said Barbara Stocking, Oxfam’s chief executive. World food prices have already more than doubled since 1990, according to Food and Agricultural Organisation (FAO) figures, and Oxfam predicts that this trend will accelerate over the next 20 years.

In its report, Growing a Better Future, Oxfam says predictions suggest the world’s population will reach 9bn by 2050 but the average growth rate in agricultural yields has almost halved since 1990. According to the charity’s research, the world’s poorest people now spend up to 80% of their incomes on food. East Africa is among the four ‘‘food insecurity hotspots’’ identified by the report – areas which are already struggling to feed their citizens. Eight million people in East Africa currently face chronic food shortages because of drought, with women and children among the hardest hit.