(CNN) -- Somalia's main militant group has banned the United Nations food agency and ordered its aid workers to leave the impoverished country.
Al-Shabaab released a statement to the media Sunday, accusing the World Food Programme of distributing expired food and undermining local farmers, said Peter Smerdon, a WFP spokesman.
Smerdon declined to comment on the accusations, but said the agency is committed to the failed nation in the Horn of Africa.
"WFP is determined to help the people of Somalia in need of assistance, regardless of who controls the areas in which they live, as long as it is safe for our staff to do so," Smerdon said.
About half the population -- or nearly four million Somalis -- is starving, according to the United Nations.
The food aid agency suspended work in southern Somalia in January, saying rising attacks and unacceptable demands from armed groups had made it impossible to work in the region.
Smerdon declined to say whether the agency had resumed operations in the south.
However, a statement on the WFP Web site says it continues to deliver food to other parts of the country, including the volatile capital, Mogadishu.
Al-Shabaab, the al Qaeda proxy in the country, controls much of southern Somalia. It has accused the food aid agency of having a political motive and supporting the U.N.-backed transitional government. WFP has denied the allegations and said it is impartial and nonpolitical.
Somalia has not had a stable government since 1991, and fighting between the rebels and government troops has escalated the humanitarian crisis in the famine-ravaged country.