At least five major cases in Afghanistan, Iraq and Africa are among the inquiries halted as the U.N. scaled back on self-policing over the past year.
The world body was rocked in the past decade when more than 2,200 companies from some 40 countries colluded with Saddam Hussein's regime to bilk $1.8 billion from a U.N.-administered oil-for-food program for Iraqi humanitarian relief.
In response, it established a special anti-corruption unit, the Procurement Task Force, in 2006 that over the next three years uncovered at least 20 other major schemes affecting more than $1 billion in U.N. contracts and international aid.
But at the beginning of 2009, the United Nations shuttered the agency and diverted its work to the Office of Internal Oversight Services' permanent investigation division.
Since then, the number of cases opened, pursued or completed has dropped dramatically and the division has let go most former task force investigators, the AP found in an examination of U.N. documents, audits and e-mails, along with dozens of interviews with current and former U.N. officials and diplomats.Read More