A global rice shortage that has seen prices of one of the world’s most important staple foods increase by 50 per cent in the past two weeks alone is triggering an international crisis, with countries banning export and threatening serious punishment for hoarders.

With rice stocks at their lowest for 30 years, prices of the grain rose more than 10 per cent on Friday to record highs and are expected to soar further in the coming months. Already China, India, Egypt, Vietnam and Cambodia have imposed tariffs or export bans, as it has become clear that world production of rice this year will decline in real terms by 3.5 per cent.

Rice prices jumped 30 per cent to an all-time high on Thursday, raising fears of fresh outbreaks of social unrest across Asia where the grain is a staple food for more than 2.5bn people.

The increase came after Egypt, a leading exporter, imposed a formal ban on selling rice abroad to keep local prices down, and the Philippines announced plans for a major purchase of the grain in the international market to boost supplies. Global rice stocks are at their lowest since 1976.

The world’s food situation is bleak, and shortsighted policies in the United States and other wealthy countries — which are diverting crops to environmentally dubious biofuels — bear much of the blame.

According to the United Nations Food and Agriculture Organization, the price of wheat is more than 80 percent higher than a year ago, and corn prices are up by a quarter. Global cereal stocks have fallen to their lowest level since 1982.

Grain farmers will need to harvest record crops every year to meet increasing global food demand and avoid famine, Potash Corp. of Saskatchewan Inc. Chief Executive Officer William Doyle said.

People and livestock are consuming more grain than ever, draining world inventories and increasing the likelihood of shortages, Doyle said yesterday in an interview on Bloomberg Television. Global grain stockpiles fell to about 53 days of supply last year, the lowest level since record-keeping began in 1960, according to the U.S. Department of Agriculture.

What is really catching the attention of Goldman Sachs now is the outlook for agricultural prices. Or as Jeff Currie, head of commodities research at the US bank, says with disarming cheer: “We think we could go into crisis mode in many commodities sectors in the next 12 to 18 months . . . and I would argue that agriculture is key here.”

Now, to some readers of the Financial Times, that observation might seem odd. After all, inhabitants of the western world typically spend far more time worrying about the price of petrol for their car, rather than the price of wheat or corn. And when western investors do think about “commodity shock”, their reference point typically tends to be the 1970s oil crisis.