DAKAR, Senegal — The United Nations appealed on Wednesday for more than $1 billion to help feed 11 million people at risk across Africa's arid Sahel belt, warning that the crisis in Syria was distracting donors from the humanitarian situation there.

The U.N. Office for the Coordination of Humanitarian Affairs (OCHA) said that this year's war in northern Mali, where a French-led military campaign destroyed an Islamist enclave, had worsened annual food shortages across the region.

Some 175,000 Malian refugees are camped in neighboring Burkina Faso, Mauritania and Niger, placing strain on scant food supplies. A further 353,000 people are displaced within Mali itself, having abandoned their homes and livelihoods.

Robert Piper, the UN regional humanitarian coordinator for the Sahel, said donor governments had provided only $607 million from an estimated $1.72 billion needed this year to help people at risk of hunger and malnutrition across the desolate region, which runs east to west across Africa.

Piper said the shortfall was partly a reflection of the financial crisis, which had reduced aid budgets in donor nations. The European Union, the United States, Japan and Britain are the main contributors to the appeal.

"Humanitarian funding is also under huge pressure now because of Syria. The amount of money required for Syria is off the chart," Piper said, noting that $4 billion from a global U.N. humanitarian appeal of $9 billion was earmarked for Syria.

The conflict in Syria has killed 100,000 people and, according to the United Nations, driven 1.7 million more to seek sanctuary outside the country.

The amount of money already spent on Mali for non-humanitarian ends could also explain donor fatigue. The deployment of a 12,000-strong U.N. peacekeeping mission from this month could cost some $700 million a year, Piper said.

"Mali is overshadowing the rest of the region a little bit. I suspect in some capitals they feel that they are doing a lot for the Sahel already," Piper said.

The worsening humanitarian situation in northern Mali, which has by far the worst nutritional statistics in the region, prompted the United Nations to increase the size of the appeal by $100 million from earlier this year.

Nonetheless, the United Nations has received less than a third of the $500 million in humanitarian donations it targeted for Mali, one of the poorest countries on earth.

WORSENING TREND

The number of people at risk from hunger this year is down from 18 million in 2012, when the nine-country Sahel region was struck by drought for the second time in three years, OCHA said.

However, that 11.3 million people remain at risk from food insecurity despite good rains reflected the region's worsening underlying humanitarian situation, Piper said.

In many markets across the region, food prices were 50 to 60 percent above their five-year average.

"The question is when are we going to start reversing the trend of ever-escalating humanitarian needs for the Sahel?" he said.

With the region's population growing at one of the fastest rates on earth, over-farming of agricultural land means that good weather is no longer sufficient to alleviate the problem.

Piper said that, with funding scarce, donor money was going to emergency food and refugee schemes, bypassing agricultural programs which could help provide a long-term solution.

The appeal has only provided around 1 million farmers from a target of 8 million with food and livestock support to make them less food insecure.