The UN must undergo sweeping reforms to prevent corruption such as that suspected during its Iraq oil-for-food programme, an inquiry has said.
Kofi Annan is expecting to be criticised in the report
The report by an independent panel was partially published a day before its release at the UN Security Council.
It found that the organisation was ill-equipped to handle the $64bn scheme and criticised the role played by UN Secretary General Kofi Annan.
It also said the scheme provided health care and food for millions of Iraqis.
There were, in fact, instances of corruption among senior staff as well as in the field
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The programme was set up in the 1990s, when Iraq was under economic sanctions, and allowed Iraq to sell enough oil to feed its people.
The report was prepared by investigators led by the former head of the US Federal Reserve, Paul Volcker, and is expected to run to nearly 1,000 pages.
It concluded that the UN failed to manage the programme and urgently needed to strengthen its leadership.
Braced for criticism
It described instances of what it termed as "illicit, unethical and corrupt" behaviour during the operation, according to the preface, released by the Independent Inquiry Commission.
"An adequate framework of controls and auditing was absent," the report said.
"There were, in fact, instances of corruption among senior staff as well as in the field."
The report pointed out that while the secretary general was supposed to be in charge of administration, in reality his diplomatic responsibilities were all-consuming, says the BBC's Susannah Price at the UN headquarters in New York.
It said that neither the UN Security Council, nor the Secretariat leadership were clearly in command of the programme and when things went wrong, important decisions were simply not made.
A spokesman for Mr Annan said he would only comment after seeing the whole report, our correspondent says.
But there is not expected to be evidence linking Mr Annan to an oil-for-food contract which was awarded to a company that employed his son, our correspondent says.
Mr Annan told BBC on Monday that he was bracing himself for strong criticism by investigators.