Sheik Ali Mohamed Hussein, an official with Al-Shabab — Somalia's most powerful militant group — said Friday that the food was expired.

Photos of the burning showed white bags of wheat bearing an American flag and the stamp USAID — the US

government's aid arm. Other bags were stamped World Food Program. Some photos showed what appeared to be old, clumpy maize.

Peter Smerdon, a spokesman for WFP, said he was checking on reports of the food burning and couldn't immediately comment. He said that WFP does not provide food for distribution that is expired.