However, the interim report released on Tuesday criticised the UN chief for not determining the exact nature of his son's relationship with a Swiss firm involved in the multi-billion dollar programme. 

The report also accused the company, Cotecna Inspection SA, and Annan's son, Kojo, of trying to conceal their relationship after the contract was awarded.

The conclusion from the report was not the clear vindication that the secretary-general had wanted, though the investigation led by former US Federal Reserve chairman Paul Volcker did not accuse the world-body chief of corruption or any other wrongdoing.

The report concluded that "there is no evidence" that the selection of Cotecna for an inspection contract under the oil-for-food programme "was subject to any affirmative or
improper influence of the secretary-general in the bidding or selection process".

Annan reacted to the finding, saying he would not resign as head of the UN and indicated he would continue to work to push through his ambitious reform plan.

"I have lots of work to do and I am going to go ahead and do it," Annan told a press conference. 

Report details

Weighing all the evidence in the 144-page report and the credibility of the witnesses, the investigators said "the evidence is not reasonably sufficient" that Annan knew
about Cotecna's bid in 1998.

But the report clearly faulted the secretary-general's management of the world body and his oversight of the $64 billion oil-for-food programme.

Volcker's Independent Inquiry Committee found that Kojo Annan was not forthcoming with either his father or the committee, and accused him of consistently trying to hide the nature of his relationship with Cotecna.

It said there were still "significant questions" about Kojo Annan's business dealings with respect to the programme, and said an investigation was continuing.