The United Nations warned Friday that Africa's Sahel region faced a serious food crisis and appealed for urgent action to save a million children at risk of malnutrition.

"With fears growing of a food crisis in the Sahel in 2012, urgent assistance is now needed," said Elisabeth Byrs, spokeswoman for the UN's Office for the Coordination of Humanitarian Affairs (OCHA).

The main factor threatening food security is the rising cost of living, with a growing number of people unable to purchase basic food goods, she said.

Tens of thousands of Africans who had been working as migrant workers in oil-rich Libya fled the conflict that led to the downfall of Moamer Kadhafi, causing a shortfall in remittances for entire communities.

The Sahel is an arid transitional zone stretching south of the Sahara desert and extending from Africa's Atlantic coast to the Red Sea.

Byrs said several countries in the Sahel belt prepared to appeal for emergency funds in 2012.

The UN Children's Fund (UNICEF) said it was working on a major operation for the region next year.

The agency said 1.02 million children from the Sahel region would be at risk of malnutrition in 2012 and said its initial appeal for $65 million (48 million euros) would be gradually increased.

According to UNICEF, the most pressing needs are in the west African country of Niger, where 330,600 children under five are estimated to be at risk.

Harvests have also been poor in many of the region's countries and northern Nigeria, Chad, Burkina Faso, northern Cameroon, Mali, Mauritania and northern Senegal are also believed to be particularly exposed.

"This children's crisis is going to be immensely challenging, we do not issue such warnings lightly, but the scale demands an appropriate response that needs to start now," said UNICEF regional director for west and central Africa, David Gressly.