The United Nations World Food Programme (WFP) said, in a statement released Monday, that it is “deeply concerned” over reports that the Islamic State group was distributing stolen food aid after relabeling the packages.

“WFP condemns this manipulation of desperately needed food aid inside Syria. We urge all parties to the conflict to respect humanitarian principles and allow humanitarian workers including our partners to deliver food to the most vulnerable and hungry families,” Muhannad Hadi, WFP’s emergency regional coordinator, said in the statement.

WFP’s statement comes hours after photographs circulating online showed militants handing out food-aid packages bearing the black and white ISIS flag. The logos of WFP and International Red Crescent can be seen below the ISIS insignia.

International Business Times has not been able to verify the authenticity of the images.

“The photographs seem to have been taken in Dayr Hafr, in eastern rural Aleppo governorate about 50 kilometres from Aleppo city.  WFP last reached Dayr Hafr on 5 August, 2014, through a cross-line convoy that delivered 1,700 food rations, enough to feed 8,500 people for one month,” WFP said, in the statement. As of now, it is not clear how the militant group got hold of the packages.

The Syrian conflict, which began in 2011 and intensified last summer after ISIS took control of vast swathes of territories in the country, has pushed the U.N. agency to its limits. In recent months, the U.N. has launched a massive appeal to donors to fund its humanitarian efforts in the region.

At least 2.5 million people are believed to have been internally displaced in the conflict-torn nation and nearly 3 million have fled across the border to the neighboring countries of Jordan, Lebanon, Iraq and Turkey.