BEIRUT: The United Nations has lost all impartiality in Syria's civil war, effectively allowing Bashar al-Assad's regime to control billions of dollars of aid, according to an investigation.
After interviewing dozens of current and former staff, researchers accused the UN of allowing Mr Assad a veto over the delivery of humanitarian supplies, "enabling" the regime's use of "sieges as a weapon of war".
Almost one million people are living in 52 blockaded areas of Syria, of which 49 are under siege by Mr Assad's forces.
The regime is denying food and medicine to the 49 rebel-held areas, according to the Syria Campaign, the advocacy group which completed the investigation.
Last year, almost 90 per cent of UN requests for aid deliveries were ignored or denied by the regime. One UN official said the number of requests was already kept low so as not to "annoy" the authorities.
The result is that most aid is distributed solely to areas under regime control. This has unintentionally bolstered Mr Assad, allowing the regime to spend less money on aid and more on military operations, as well as posing as a reliable provider of help.
Assad's starvation tactic has forced hundreds of thousands of people out of rebel-held enclaves and into areas under the regime's control.
The report, released on Wednesday, outlines how the UN's fear of being asked to leave Damascus has led to "far-reaching and unnecessary" capitulations to Mr Assad.
This has included downplaying his regime's role in enforcing blockades, revising down the number of people living in besieged areas, and taking rebel-held towns such as Madaya off the list at a time when residents were starving to death.
People in besieged have to buy food on the black market, paying up to 100 times the cost.Baby milk formula in Damascus costs 500 Syrian pounds (pounds 1.50), while in the besieged suburb of Daraya it sells for nearly 30,000 Syrian pounds (pounds 96).
Bissan Fakih of the Syria Campaign, said: "A UN with the backbone to stand for its principles would help get aid to hundreds of thousands of Syrian civilians under siege, many of them only a few minutes' drive from where the UN is based in Damascus."
Roger Hearn, a former head of the UN Relief and Works Agency in Damascus (UNRWA) - the branch of the UN charged with helping Palestinian refugees - said: "There has been a systematic failure in the UN-led response. Rather than basing its response on need, it has developed into a billion dollar response programme that is largely controlled by the regime and its proxies."
The UN did not respond to the Telegraph's request for comment.