Turnbull denies passing on fake email

Opposition Leader Malcolm Turnbull denies giving a fake email at the centre of the OzCar affair to a newspaper, and suggests someone in Treasury could be the culprit.

The Daily Telegraph reported on Saturday it had an email suggesting Prime Minister Kevin Rudd's office had made representations on behalf of his friend and Queensland car dealer, John Grant, in an effort to help the car dealer gain access to a taxpayer-funded finance scheme.

The Australian Federal Police said on Monday the email was a forgery, following a search of Treasury official Godwin Grech's home.

Mr Turnbull said the opposition could not be held responsible if the fake email came from a person in Treasury, suggesting Treasurer Wayne Swan should be reprimanded if that was the case.

"I cannot be held responsible for an email that was concocted, if it was concocted, by somebody else," Mr Turnbull told ABC Television.

"If the email was concocted in the Treasury, then Mr Swan should be answering for it."

Mr Turnbull said no one in the opposition had provided a copy of the fake email to the newspaper.

"I can tell you categorically that nobody in the opposition provided the text of that email to Mr (Steve) Lewis," he said.

He also refuted Mr Rudd's assertions the opposition had said he was corrupt.

"I've never accused him of corruption, I've never used that word."

Mr Rudd said he knew the email was fake as early as Friday night.

"You should know that here in Canberra, the corridors of power and the media talk a lot ... this has been one of the worst kept secrets ... over the last couple of weeks," he told ABC Television

Meanwhile earlier on Monday night, Prime Minister Kevin Rudd turned the tables on Mr Turnbull, calling on senior Liberals including Brendan Nelson, Peter Costello and Nick Minchin to "tap him on the shoulder" and tell him to apologise and resign.

"The entire basis for his allegation, this email, is a fraud, it is a fake, it is a fabrication," Mr Rudd told the Nine Network.

Mr Rudd backed Mr Swan saying that all of the car dealers who had approached the government "were dealt with in the same way".

He said the use of a forged document raised questions about Mr Turnbull's character.

"He does not have the character to occupy the highest office in the land," Mr Rudd said.

Mr Rudd also requested on Monday that Auditor-General Ian McPhee extend his investigation into the email to representations to car dealers by Mr Swan's office and to Treasury.

Mr McPhee is due to report to parliament on July 31.

The AFP investigation also threatened to reach the opposition leader's office with police confirming they were keen to interview Paul Lindwall, a former adviser in Mr Turnbull's office. Mr Lindwall has denied any involvement with the fake email.

A police statement said they had conducted a "forensic investigation" of computers at Mr Grech's home and at the Department of Treasury.

"Preliminary results of those forensic examinations indicate that the email referred to at the centre of this investigation has been created by a person or persons other than the purported author of the email," the police statement said.

Police said a 42-year-old man from suburban Calwell in Canberra had been interviewed in relation to the matter and that the investigation was continuing.

Moving a censure motion in parliament, which was defeated along party lines, Mr Turnbull said the case against Mr Swan did not rest or rely on the email allegedly sent from the prime minister's office to Mr Grech.

He called on the government to set up a judicial inquiry into the OzCar affair with a brief to examine the relationships of Mr Rudd's and Mr Swan's offices, Treasury and car dealerships.

But Mr Swan's office released 22 emails on Monday night to and from Dr Charlton and Mr Grech, other officers in Mr Swan's office and Treasury officials including secretary Ken Henry and his deputy Jim Wright.

They show communication between officials concerning two unnamed car dealers - their names were blacked out in the emails provided by Mr Swan's office - on how efforts were proceeding in terms of the dealers gaining finance.

Mr Swan said on Monday night that he stood by his remarks in parliament on June 4 that many representations were made on behalf of many dealers and all were dealt with in the same way and passed on to Treasury.

"This correspondence goes beyond doubt that other car dealers were receiving as much, if not more, attention from the Treasury as it went about its proper task of assisting dealers to find alternative finance," Mr Swan said in a statement.

His comments were backed on Sunday by Motor Trades Association of Australia executive director Michael Delaney, who said he was aware of many dealers receiving the same treatment as Mr Grant.