Opposition Leader Tony Abbott has accused Prime Minister Kevin Rudd of organising a dirt campaign against him over an incorrect claim for travel expenses.

Mr Abbott has had to repay more than $9,000 in taxpayer funding, including the use of official "comcars", which was spent on travel to promote his book Battlelines in 2009.

Controversial former Liberal National Party MP Peter Slipper has complained about the case because he is facing legal action over travel expense claims of less than $1,000.

"No credit to justice when cases are treated differently. Abbotts amt was $9400 and he has been let off," Mr Slipper, who now sits as an independent, posted on Twitter yesterday.

Mr Slipper said the Opposition Leader had been given preferential treatment.

But, facing persistent questioning today in a press conference during a visit to a Sydney pie-making business Mr Abbott said it was a mistake that has been dealt with and was "old news".

"The Labor minister at the time was perfectly satisfied that there had been nothing that was deliberately done wrong and the matter was closed," he said.

"I think I've fully dealt with it, time to move on."

When pressed further, he accused the Prime Minister of stirring up the issue.

"Why is Kevin Rudd now trying to dish this sort of dirt?" he said.

"Kevin Rudd came into the prime ministership a few days ago and he said let's have a kinder, gentler polity .. and he called for positive politics, now we've got the Labor Party spinning this kind of stuff. Now, let's move on."

A spokeswoman for Mr Rudd has rejected the accusation, saying Mr Abbott's travel expenses are a matter for him to explain.

Details of the travel expenses claim were revealed over the weekend on an independent website.