As much as half the food aid sent to Somalia is diverted from needy people to a web of corrupt contractors, radical Islamist militants and local United Nations staff members, according to a new Security Council report.

The report, which has not yet been made public but was shown to The New York Times by diplomats, outlines a host of problems so grave that it recommends that Secretary General Ban Ki-moon open an independent investigation into the World Food Program’s Somalia operations. It suggests that the program rebuild the food distribution system — which serves at least 2.5 million people and whose aid was worth about $485 million in 2009 — from scratch to break what it describes as a corrupt cartel of Somali distributors.

In addition to the diversion of food aid, regional Somali authorities are collaborating with pirates who hijack ships along the lawless coast, the report says, and Somali government ministers have auctioned off diplomatic visas for trips to Europe to the highest bidders, some of whom may have been pirates or insurgents.

Somali officials denied that the visa problem was widespread, and officials for the World Food Program said they had not yet seen the report but would investigate its conclusions once it was presented to the Security Council next Tuesday.