NAIROBI, Kenya (AP) — The United Nations food relief agency has suspended aid deliveries to Ethiopia’s northern Tigray region amid an internal investigation into the theft of food meant for hungry people, according to four humanitarian workers.

The World Food Program is responsible for delivering food from the U.N. and other partners to Tigray, the center of a devastating two-year civil war that ended with a ceasefire in November.

More than 5 million of the region’s 6 million people rely on aid.

WFP informed its humanitarian partners on April 20 that it was temporarily suspending deliveries of food to Tigray amid reports of food misappropriation, one of the four humanitarian workers told AP. Three other aid workers confirmed this information. They all insisted on anonymity because they were not authorized to speak to a journalist on this matter.

Last month, AP reported that the WFP was investigating cases of food misappropriation and diversion in Ethiopia, where a total of 20 million people need humanitarian help due to drought and conflict.

A letter sent by the WFP’s Ethiopia director on April 5 asked humanitarian partners to share “any information or cases of food misuse, misappropriation or diversion that you are aware of or that are brought to your attention by your staff, beneficiaries or local authorities.”

At the time, two aid workers told AP that the stolen supplies included enough food to feed 100,000 people. The food was discovered missing from a warehouse in the Tigray city of Sheraro. It was not clear who was responsible for the theft.

Tigray’s new interim president, Getachew Reda, said last month he discussed “the growing challenge of diversion & sale of food aid meant for the needy” with senior WFP officials during a visit by the agency to Mekele, the regional capital.

A spokesperson for the WFP in Ethiopia did not immediately respond to a request for comment.