Senior counsel assisting the inquiry, John Agius SC, said Prime Minister Howard could appear at the Cole inquiry as early as Thursday to give evidence.
Speaking outside the court on Monday evening, Mr Agius said he expects to receive Mr Howard's statement before Wednesday.
"I expect that on Wednesday we will be asking people to inform the inquiry as to whether they have any wish to examine the prime minister in relation to his statement," he told reporters.
"If he is called, either because I want to examine him, or because the commissioner grants any application that might be made (to cross-examine Mr Howard), I hope we can do it on Thursday."
The inquiry, headed by former judge Terence Cole, is looking into the payment of bribes to Saddam Hussein's regime in Iraq in defiance of United Nations sanctions.
Vaile denies seeing cables
Mr Vaile said he had not seen a batch of 21 confidential diplomatic cables sent since 2000 outlining concerns about AWB's dealings in Iraq
Included in the emails was one from Australia's trade commissioner in Washington, Alistair Nicholas, urging his bosses in Canberra to alert Mr Vaile to allegations that AWB's contracts contained irregularities.
"In the context of this inquiry when we came across the cable and when I read the cable ... I must admit I was surprised that it hadn't been brought to my attention," said Mr Vaile after he was asked by Mr Agius if he should have been shown such a cable.
Mr Vaile said at the time he had only been trade minister for six months and was "snowed under" by his new responsibilities, including the troubled World Trade Organisation talks.
The inquiry has been told AWB paid nearly $300 million in kickbacks to Saddam Hussein's government by paying "trucking fees" to a Jordanian-based transport firm, Alia, which was part-owned by the Iraqi government.
In a 16-page statement tendered to the inquiry, Mr Vaile said he was not told about Alia funnelling kickbacks to Saddam Hussein's regime until March 30, 2004, when the United Nations announced its inquiry into corruption of its oil-for-food program in Iraq.
Foreign Minister Alexander Downer will appear before the inquiry on Tuesday.
They are the first senior ministers to be called to account by a commission of inquiry in more than 20 years.
The ministers are being asked about what they knew of the AWB kickbacks.
They have maintained that they were either unaware of specific warnings, believed the charges were concocted by competing wheat exporters in Canada and the US, or accepted denials by AWB executives.
Howard to give statement
Mr Howard earlier agreed to provide a statement to the inquiry by four o'clock on Tuesday afternoon.
"As I have previously indicated, if I am asked to appear before the inquiry, I will be happy to do so."
Mr Howard said he has nothing to hide.
"I've said all along this is an utterly transparent process which is not protecting the government but which is designed to get to the truth of this matter, and I'm more than happy to comply with the request made by the commission."
At the same time a former United Nations officials claims that the Australian government failed six years ago to act on key warnings that wheat exporter AWB was making "shameful" illicit payments to Iraq.
Felicity Johnston, a UN customs chief, has broken her silence on the scandal, saying she warned Australian officials six years ago that AWB might be breaching sanctions.
But Mr Howard has rejected her comments.
Mr Agius said Ms Johnston has been asked to provide a sworn statement to the inquiry’s head.
She was the chief customs officer for the UN Office of Iraq Program between 1999 and 2003.
Canada told the UN in early 2000 that AWB was making illicit payments to Iraq in the form of inland transport or trucking fees, prompting investigations.
The commission of inquiry is examining whether Australian law was broken by the wheat exporter and whether any of those connected with the company should be prosecuted.