Swan calls for Turnbull to resign over email

Wayne Swan has called for Malcolm Turnbull to "put up or shut up — and resign" over the OzCar email affair.

Speaking to Laurie Oakes on TODAY this morning, the treasurer denied offering any improper assistance to Ipswich car dealer John Grant and maintained the government's line of attack on the opposition leader.

"He's got 24 hours to produce this email or resign," Mr Swan said.

"It's the basis of a smear not only against the Prime Minister but also the Treasurer."

Mr Swan accused Mr Turnbull of "running away at a million miles an hour and terminating the doorstop" when the issue was raised yesterday.

"He's got some very serious questions to answer," Mr Swan added.

The government has ordered the Australian Federal Police (AFP) to investigate whether someone impersonated one of Mr Rudd's senior economic advisers, who's accused of emailing a Treasury official on behalf of Mr Grant.

Prime Minister Kevin Rudd has consistently denied he, or his office, made representations on behalf of Mr Grant, a mate and Queensland neighbour.

The opposition and some newspapers claim to have seen the contents of an email from Rudd adviser Andrew Charlton to OzCar boss Godwin Grech - but no one's produced a hard copy yet.

Mr Rudd says it's time for Mr Turnbull to put up or shut up.

"Mr Turnbull has some grave questions to answer in relation to his own credibility and integrity on this matter," the PM told reporters in Canberra yesterday.

The opposition leader claimed mid-week to be in possession of documentary evidence that proved Mr Rudd's office lobbied on behalf of Mr Grant.

"Today Mr Turnbull is in full retreat on this claim," Mr Rudd said.

"How easy it is in the business of national politics simply to throw mud at people and then, having thrown the mud, to run away."

Mr Turnbull admits he doesn't have an actual copy of the email, but insists the Liberal Party didn't falsify it.

"The email was not provided to (the media) by anyone in the opposition ... and was not composed by anyone in the opposition," Mr Turnbull said, adding the prime minister was "trying to run a distraction as usual".

Finance Minister Lindsay Tanner isn't convinced.

He says the fact Mr Turnbull mentioned the email to Dr Charlton on Wednesday at the press gallery ball means "it would appear likely that the Liberal Party is the source".

If the email can't be produced, the case against Mr Rudd rests on the word of Mr Grech.

The Treasury official told a Senate inquiry on Friday he believed "the initial contact that I had with respect to John Grant was from the prime minister's office ... in a short email".

Mr Tanner tried to discredit that testimony on Saturday, describing it as "confused and vague".

"It's very odd that somebody would make an assertion of this kind where he's unable to produce the email, and then he immediately says `But my memory could be wrong, I may be in error in making that statement'," the finance minister told reporters.

Whether or not Treasurer Wayne Swan lied to parliament is less ambiguous.

The government itself has released a series of emails that show his office lobbied on Mr Grant's behalf.

But the treasurer says he never denied passing on representations from Mr Grant - only that he didn't know the outcome.

"I stand by the comments I made to parliament and nothing that has been raised in the last 24 hours contradicts what I said to parliament," Mr Swan told reporters.

As to emails regarding Mr Grant being sent to Mr Swan's home fax in Brisbane, the treasurer said Mr Grech simply hit a "reply all" button that automatically sent the messages.

But Mr Turnbull said the fact Mr Swan helped Mr Grant in the first place meant he had to go.

"He used the enormous influence of the commonwealth government to seek to secure an advantage for a mate and benefactor of the prime minister," the opposition leader said.

"He should tender his resignation."

The AFP criminal investigation will run concurrently with an auditor-general's inquiry into any links between the PM's or the treasurer's office and Treasury regarding Mr Grant.

Mr Rudd says Mr Turnbull should commit to "full cooperation" with the police inquiry.

He also wants his rival to explain who provided the contents of the "fake email" to the opposition, who read it and what they did with it afterwards.