The political upheavals that have swept Africa in recent months, especially Libya's civil war, have accelerated a food crisis in the Sahel, a drought-plagued, semi-desert region that spans the continent.

The Sahel runs for some 4,000 miles from the Atlantic Ocean to the Red Sea and embraces some of the world's poorest countries like Mali, Niger and Chad.

The United Nations' Food and Agriculture Organization has warned that 16 million people in the region will suffer food shortages this year because of poor rainfall and the wave of violence triggered by the eight-month Libyan conflict in 2011.

The FAO said Niger's cereal output fell 25 percent in 2011 and the drop was 50 percent in Mauritania and Chad. There have been severe drought warnings in Cameroon, Burkina Faso, northern Nigeria, Mauritania, Senegal and Gambia.

UNICEF officials said they were bracing to treat more than 1 million children for severe malnutrition.

Life is tough in the Sahel in normal times but the fallout from the Libyan bloodletting, the spillover of unrest that resulted in the March 21 coup in Mali by Tuareg rebels and the Islamist insurrection in Nigeria to the south have combined to fuel the crisis sweeping the region.

Thousands of refugees fleeing these convulsions have puts a heavy strain the Sahel's slender food resources, already worsened by the ever-present cycle of drought that caused severe crises in 2005 and 2010.

Refugee numbers are hard to come by but aid activists estimate that some 200,000 people have been displaced in northern Mali by the Tuareg rebellion, which resulted in the overthrow of the country's elected president, Amador Toure.

"This year there's been one factor on top of another," observed Madeleine Evrard Diakite, adviser for the British charity Oxfam in neighboring Niger.

"It's a cocktail which is putting enormous strain on households across the region."

Another aid group, World Vision, said thousands of hungry, exhausted refugees had fled to Niger.

The government there "is struggling to cope with the influx and the extra strain is pushing families to the brink of survival," said Chris Palusky, World Vision's food crisis response manager for Mali and Niger.

On top of this, migrant workers from Niger and Chad who depended on work in oil-rich Libya have had to flee, cutting off a key income source and stretching scarce food supplies.

An estimated 280,000 migrant workers from Niger have returned from Libya to a country already straining to feed its population of 16 million.

The Tuareg have seized control of the remote northern part of landlocked Mali, including the fabled city of Timbuktu, and declared it the independent state of Azawad.

But their rebellion, which erupted in January when Tuareg tribesmen recruited by Libyan dictator Moammar Gadhafi returned from the Libyan war with heavy weapons, has been emphatically condemned by the United Nations and African organizations.

The United States, France and the European Union cut off all but essential humanitarian aid to Mali, with a population of 13.5 million, as its neighbors sealed off its borders and imposed an embargo.

The humanitarian organization Oxfam reported that the country could soon grind to a halt since it imports all its fuel and most of its needs.

"Some 3 million to 5 million people are at risk as the country has been hit by one of the worst food crises in decades," declared Eric Mamboue, Oxfam's country director in Mali.

"We're concerned that some of the sanctions imposed by neighboring counties and supported by the U.N. Security Council … could serve to make an already desperate situation even worse."

Food prices have soared as scarcity has worsened. Large numbers of people from the countryside have decamped to nearby cities, including Niamey, capital of neighboring Niger, to beg on the streets.

A swelling insurrection in northern Nigeria by Islamist zealots of the Boko Haram -- "Western education is sinful" -- movement in which thousands of people have perished, has cut off food imports to the Sahel countries from Africa's most populous nation.

Amid fears that Boko Haram has established links with the North African jihadists of al-Qaida in the Islamic Maghreb, another force destabilizing the region, trade in livestock from the south has heightened the crisis in the Sahel.