The U.N. World Food Program is investigating two of its top officials in Sudan over allegations including fraud and concealing information from donors about its ability to deliver food aid to civilians amid the nation’s dire hunger crisis, according to 11 people with knowledge of the probe.

The investigation by the WFP’s Office of the Inspector General (OIG) comes as the U.N.’s food-aid arm is struggling to feed millions of people in war-plagued Sudan, now suffering one of the world’s most severe food shortages in years.

As part of the probe, investigators are looking at whether WFP staff sought to hide the alleged role of Sudan’s army in obstructing aid amid a brutal 16-month war with a rival paramilitary for control of the country, according to five of the sources who spoke to Reuters.

One of those being examined in the inquiry is the WFP’s deputy country director in Sudan, Khalid Osman, who has been given a “temporary duty assignment” outside Sudan, a de facto suspension, according to six sources.