Federal police have spoken with Opposition Leader Malcolm Turnbull about the fake email affair.
The police want to know who created the fake email, which indicated Prime Minister Kevin Rudd was seeking favours for a car dealer mate.
The opposition knew about the email early and used it to point the finger at Mr Rudd.
The attack backfired, leading to a horror week for Mr Turnbull.
"I've met with the federal police, I've given them a statement," Mr Turnbull told the Ten Network on Sunday.
"Let the police do their work."
He vowed his team would be more careful in the future after the email affair, appearing to broaden responsibility by using "us" and not "me".
"I think everyone will be more cautious, all of us will be cautious.
"You've got to learn from episodes like this."
Recent events have led to speculation that some Liberals are not happy with Mr Turnbull's leadership.
He denied his authority had been diminished.
"The party is united. Certainly we've had a tough week, there's no doubt about that.
"I don't think you've ever seen an opposition pull together more tightly and fight back more strongly than we did during this last week.
"The biggest lesson is that there's always adversity in politics and you have to deal with it and move on."
Mr Turnbull complained that the government had it in for him from the start. They have called for him to resign and raised issues from Mr Turnbull's past since the email affair broke.
"All they have been flinging against me, in fact they've been doing it ever since I became leader, is one smear after another."
Mr Turnbull said the government had been "vicious and personal" in their "fear and smear" attacks on him.
The opposition on Thursday voted down a proposal to have a parliamentary committee investigate whether false evidence or documents had been presented to the original OzCar enquiry.
Mr Turnbull defended the move, saying such an inquiry would not have been fair.
"An inquiry of that kind in this climate would be purely a political witch-hunt."
He said a full, open, judicial inquiry into the OzCar issue would be appropriate but the government would not allow it.
Mr Turnbull sought to distance himself from the fake email, saying he had relied on the testimony of senior Treasury official Godwin Grech, rather than on the email.
"I did not rely on (the email) in making my criticism of the prime minister."
Mr Turnbull, when grilled on the state of his leadership authority, said there was no basis for the claim that it had been diminished by the fake email affair.
"I don't accept that criticism."
Meanwhile, the government says the opposition has cut loose Mr Grech.
Liberal MPs have told the media that Godwin Grech, who was in charge of the $2 billion OzCar financing scheme, had been leaking information to the coalition since the days of the Howard government.
Finance Minister Lindsay Tanner said Mr Turnbull's failure to disown the media reports about Mr Grech showed the coalition was using the public servant for political purposes.
"Mr Turnbull on the one hand is all popped-up and pompous about parliamentary privilege and protecting the ability of public servants to leak and yet he had his own troops out there backgrounding journalists, more or less saying that Godwin Grech was a serial leaker to the Liberal Party," Mr Tanner told the Nine Network.
"He's dumped Mr Grech right in it in order to save his own skin.
"So whether or not any of that's true, I don't know.
"Mr Turnbull, by not denying these suggestions... is showing a clear willingness just to cut Mr Grech loose and let him hang."
However, coalition finance spokeswoman Helen Coonan said the public would support the opposition for having a go if it received a tip-off.
"If you receive, what on the face of it looks like credible evidence, you wouldn't get many votes if you don't have a go," Ms Coonan told Sky News.
Ms Coonan said Mr Turnbull did not mishandle his pursuit of the prime minister.
"In hindsight, what you actually see here is a set of circumstances that Mr Turnbull admitted didn't establish his case against Mr Rudd," she said, adding other evidence showed Treasurer Wayne Swan had given special treatment to one car dealer out of 240 who had inquired about OzCar.
AAP
