More than 70 humanitarian organizations are accusing the United Nations of allowing the Syrian government to manipulate relief efforts and keep desperately needed aid from thousands of people in besieged areas.

The aid groups working in Syria and neighboring Jordan, Lebanon and Turkey announced that they are suspending participation in an information-sharing program aimed at improving aid deliveries as a first step to protest the Syrian government's "political influence" and the inaction of Damascus-based U.N. agencies and humanitarian organizations.

In a letter to the U.N. humanitarian office in Turkey, obtained Thursday by The Associated Press, the 73 groups also called for an investigation into criticism of the U.N.'s performance.

U.N. spokesman Stephane Dujarric praised the work of the groups and said "we're going to continue to engage with them."