Work must begin "at once" to prevent a disastrous food crisis in West Africa, according to UNICEF Executive Director Anthony Lake.
"More than one million children in the Sahel region of Africa could face life-threatening malnutrition in 2012 if the global community does not take immediate action," Lake said in a statement.
Poor harvests are putting the lives of many hundreds of thousands of children and families at risk across the Sahel region of West and Central Africa.
In Niger, more than 330,000 children under five are at risk of severe or acute malnutrition. Crops have failed this years and a new crisis seems inevitable.
Other countries and regions where children are expected to need specialist treatment are Chad, northern Nigeria, the north of Cameroon, Burkina Faso, Mali, Mauritania and northern Senegal.
To prevent a wide-scale emergency, UNICEF and its partners are making sure the countries in the region are well prepared for a crisis by providing them with life-saving supplies before it is too late.
"The children at risk today in the Sahel are not mere statistics by which we may measure the magnitude of a potential humanitarian disaster," Lake said.
"They are individual girls and boys, and each has the right to survive, to thrive and to contribute to their societies. We must not fail them. The challenge is great and the window is closing."