Appearing before the Cole inquiry by video link, former chief UN customs officer Felicity Johnston stood by claims she made last month which have put her directly at odds with an Australian official who was based in the United States.
The Cole inquiry, which sat for the last time on Friday, heard two very different stories about what Australian diplomat Bronte Moules was told about the allegations against AWB.
Ms Johnston told the commission via video link from Washington that she phoned Ms Moules in January 2000 to discuss a complaint from Canadian authorities about irregularities in AWB's contracts.
Ms Johnston maintained she warned Ms Moules about transport fees now known to be worth nearly A$300 million being funnelled to Saddam Hussein's regime in Iraq through Alia, a Jordanian trucking company.
Her lawyer, Keith Harrison, asked: Is it a fact that you told Ms Moules... all the facts that you were aware of?”
Ms Johnston answered: "Yes, that's correct."
The evidence is in stark contrast to that of Bronte Moules who's repeatedly told the commission that there was no mention of concerns about the potentially illegal payments.
Under cross-examination, Ms Moules was asked why a cable she wrote in 2001 alerting Australian officials about UN concerns over kickbacks to Iraq was sent to the commission by the department of fisheries and not her department, and why the cable had not been made available when she twice gave evidence.
Commissioner Cole interjected, rejecting both questions.
Earlier, Ms Johnston told the inquiry that AWB's contracts were not closely scrutinised because of the company's good reputation and the urgent need for wheat in Iraq.
She also said UN staff had a tacit understanding that breaches of sanctions on Iraq could not be prevented.
Counsel assisting the commission, John Agius, asked Ms Johnston "was that an essential weakness or a fatal flaw?"
Ms Johnston replied, "Aren't they one and the same."
Mr Agius replied, "Perhaps they were."
India shipment
Adding to AWB's woes, a 400-thousand tonne shipment of wheat to India has been held up at Australian ports over quality concerns.
Part of the A$90 million consignment was rejected last month after claims the wheat contained unacceptable levels of pesticide.