THE billboard at the side of the dusty road offers what the land it stands on cannot provide a sack of grain, the top prize in an advertising campaign sponsored by a mobile phone company.

Here in Niger, lottery winners win food. And looking beyond the signs along the sweltering route to Tillaberi — a region 30km from the capital, Niamey, on a road which stretches north into the Sahara desert and Timbuktu — it is not hard to see why.

Fields of stunted millet stand baking in the 35C heat, a land pocked by dry river beds, and the occasional carcass of a starving cow. This is a picture of hunger — one that is raising increasing concerns from international aid bodies and humanitarian organisations.

Nearly 12 million people in Niger — about 80 per cent of the population — are now affected by food insecurity, a status that indicates they have as few as 10 days' food supplies remaining with all other income-generating activities exhausted.

Without urgent assistance, there are fears that many will starve. The causes of the crisis are complex. Last year, exceptionally heavy rainfall destroyed crops and devastated this year's harvest. The resulting fall in production in staples like maize, millet and sorghum has affected much of West Africa's Sahel — fragile in the best of times — including neighbouring Chad and northern Nigeria.

But Niger is the country most greatly affected, in particular its children, 17 per cent of whom are already malnourished, well above the 15 per cent threshold for an emergency. Save the Children now estimates that as many as 400,000 children in Niger are facing starvation.

Aid agencies have been monitoring levels of food insecurity since 2005, when the last crisis was triggered by drought and locusts destroyed much of the previous year's food production.

But the extent of today's food crisis — and the deterioration of so many children's nutritional status in particular — has taken many by surprise.

“These are very high levels of child malnutrition, the situation is bad,” said Gianluca Ferrera, deputy director for the UN World Food Programme in Niger. “The loss in harvest last year was worse than expected, and the lean season started earlier than anticipated for a larger share of the population. In some areas, there is a 50 per cent malnutrition rate for children under two. Many of these children will not survive.”

Fatoumata Soumana, disaster risk and emergency response adviser for the Niger branch of Plan, a non-governmental organisation, said the situation was getting worse. “In some areas, things are worse than in 2005.” Plan invited the Guardian to Niger out of concern for the lack of media coverage of the crisis.

The paradox of this year's worsening food shortage is the presence of plentiful quantities of food in many markets throughout the country. “There is a relatively good flow of food into the markets in Niger, yet prices remain extremely high,” said Ferrera. “Since 2008 there has been a lot of speculation and tension in the markets. There has been good food production in neighbouring countries, yet prices are abnormally high.”

The potential for high food prices to cause food insecurity and famine has been criticised in recent years. Speculation in agricultural commodities on the international financial markets since 2006 has been blamed for price increases of up to 300 per cent for some basic foodstuffs, including rice and cereals, a phenomenon described by UN special rapporteur on the right to food, Jean Ziegler, as “silent mass murder”.

— The Guardian, London