The agency said that the photographs appeared to have been taken in Dayr Hafir, about 30 miles east of Aleppo in an area controlled by the Islamic State.

“We were not providing assistance to these areas, so we need to find out what was going on,” Stefano Porretti, the World Food Program’s director of emergencies, said in a brief telephone comment.

The United Nations agency said it last reached Dayr Hafir in August, sending a convoy carrying 1,700 boxes of rations with basic supplies like rice and wheat flour to meet the needs of 8,500 people for a month.

The program distributes food for more than four million people in Syria each month, much of it through the Syrian Arab Red Crescent, a crucial partner for most international aid agencies working in Syria. However, S.A.R.C.’s warehouse in Dayr Hafir was seized by the Islamic State in September, and there has been no contact with workers there since then, the World Food Program said.

“We put the pieces together and realized that this probably was whatever was left in the warehouses,” said Abeer Etefa, a spokeswoman for the food agency in Cairo. “In this particular area, no one has access; we have not operated there since September.”