Somalia, a country of nine million people, already imports more than half its grain needs.

Soaring commodity prices and a weakening currency have made those staples 375 percent more expensive than a year ago, the FAO said in a statement.

Many households did not have enough money to meet basic needs, said the FAO's Somalia Adviser, Cindy Holleman, in the statement.

Drought in parts of the country and poor rainfall in others meant domestic food production was also likely to be well below normal.

"If the Gu (mid-April to June) rains are significantly below normal, the shilling continues to lose value, food prices increase further and civil insecurity worsens, we could see as many as 3.5 million people ... facing acute food and livelihood crisis or humanitarian emergency conditions by the end of the year," Holleman said.

She said the number of people in Somalia needing aid had increased by 40 percent since January. A million more could be affected by the end of the year, especially if the rains fail.

The security situation was another threat. The number of Somalis fleeing the capital Mogadishu, one of the world's most dangerous and heavily armed cities, increased by 20 percent since January to 855,000, the statement said.

The country has more than 1 million internally displaced people, the UN body estimates, and has called for $18.4 million to help Somalis but received only a quarter of that.