A report by the pro-opposition advocacy group, the Syria Campaign, has accused the United Nations of a “serious breach of the humanitarian principles of impartiality, independence and neutrality.” The newly released report says that the agency is bowing to the demands of President Bashar Assad’s government and delivering 99 percent of its aid to government-controlled territories.

The 50-page report is based on interviews with over 50 aid workers, both Syrian and international, U.N. officials, evaluators of U.N. agencies and Syrians living under siege who have worked on humanitarian relief. It is also signed by at least 62 Syrian civil society organizations.

Former head of the U.N. Relief and Works Agency in Damascus, Roger Hearn, reportedly said, “There has been a systematic failure in the U.N.-led response. Rather than basing its response on need, it has developed into a billion-dollar response program that is largely controlled by the regime and its proxies.”

The report titled, “Taking Sides: The United Nations' loss of impartiality, independence and neutrality in Syria,” stated that in April this year, 88 percent of food aid delivered from inside Syria went to government-controlled territories and a mere 12 percent reached those outside the government’s control. The report alleged that the U.N.’s compliance has allowed Assad's regime to veto aid deliveries to besieged areas.

The report also said that the U.N.’s fear of having visas revoked or being asked to exit the country has led to an unnecessary “culture of compliance” among agencies in Damascus, the capital city of Syria. It accused the U.N. of transferring billions of dollars in aid to just one side of the conflict, prioritizing government cooperation over civilian deaths due to lack of access to basic necessities.

U.N. spokesman Stephane Dujarric told Al Jazeera that describing “the U.N. humanitarian work in Syria as not being impartial or not being fair, discredits the amazing work of our colleagues, mostly Syrians, are doing every day to try to deliver aid to the Syrian people.”

The group, in the report, demanded the U.N. to set the terms of its humanitarian aid in Syria in a way that would protect the international body’s humanitarian principles or withdraw its cooperation with the Syrian government.

The country is in the middle of a multisided war that began in March 2011. A report by a U.K.-based monitor Monday said that at least 224 civilians were killed in just one week.