The report also said that almost half a billion children risk are at risk of permanent damage over the next 15 years.

Wednesday's report from Save the Children said the deaths of two million children each year could be prevented if malnutrition were better addressed.

The report called chronic malnutrition a largely hidden crisis that affects one in four children globally. Global hunger has fallen markedly over the past two decades, but the 2011 Global Hunger Index found that six countries have higher rates of hunger today than two decades ago. Five of those countries are in Africa. The other is North Korea.

The 2011 Global Hunger Index said that Congo, Burundi, Comoros, Swaziland and Ivory Coast have higher degrees of hunger today than in 1990. Kuwait, Turkey, Malaysia and Mexico have made the biggest gains against hunger.

Karin Lapping, a senior director of nutrition for Save the Children, said many Asian countries have made strides against hunger because of an explicit focus on reducing chronic malnutrition, but that many African countries have not made that same commitment and have fallen victims to predictable cycles of drought and famine.

"When we look at successful examples in Asia like Bangladesh, they have a national nutrition program," Lapping said. "We haven't seen that to be the case in many nations in Africa."

Ethiopia is one exception, she said, because of successful nutrition programs. But, she said, in many other regions "progress has been undercut by cyclical emergencies like what we're seeing now in the Sahel," a belt across northern Africa that experiencing a food crisis.

Lapping said many African countries need greater political commitments from their governments and more external aid.

Malnutrition numbers in Africa remain startling. The report said that nearly two in five children on the continent – 60 million children - are stunted. The average yield of staple cereals is a third less than in Asia.

The British government estimates that between 50 000 and 100 000 people died during a famine in Somalia last year. Most of those killed were children.

Chronic hunger leaves children vulnerable to starvation when food crises hit, but also leaves them vulnerable to death by diarrhoea, pneumonia and malaria even in better times.

"It also likely causes permanent damage to their bodies and brains," said Tanya Weinberg, a Save the Children spokeswoman.

The Save the Children report said that if action is not taken to reduce chronic malnutrition, 450 million children will be affected by 2025.

The report said that malnutrition must be made more visible so that governments are forced to act, that more health care workers are needed and that governments must help small-scale farmers improve their yields.