Unequal treatment of Slipper: Albo

Labor leadership contender Anthony Albanese believes former Speaker Peter Slipper has been treated harshly over travel expense claims when compared to senior members of the Abbott government.

Mr Slipper is upset that other MPs have been allowed to repay errant expense claims, while he faces court.

Asked on ABC radio if he thought Mr Slipper had been treated unfairly, Mr Albanese said one could "draw a conclusion that ... (there's been) unequal treatment."

"People must have noticed the way in which the coalition went after Peter Slipper, who's now before the courts over a claim that's much less than the money that has had to be paid back (by coalition MPs)."

Mr Slipper has pleaded not guilty to charges arising from his use of a government Cabcharge card for a tour of wineries in the Canberra area.

A number of senior coalition MPs have repaid questionable travel claims in recent days, including one Prime Minister Tony Abbott lodged for attending Mr Slipper's wedding in 2006.

Fellow Labor leadership aspirant Bill Shorten says expense claim guidelines should be simplified.

"I think most members of parliament wouldn't deliberately diddle their expenses," he told ABC radio.

"But I also think this recent controversy shows that the guidelines need to be as unambiguous and as black and white as possible." The sort of discussion going on at the moment undermined confidence in the system, Mr Shorten said.

Labor frontbencher Mark Dreyfus was more critical of the coalition's link to expense claims.

"Clearly there is a definite scope for some serious investigation," he told ABC Radio.

Professor Allan Fels, who was part of a 2010 committee review of parliamentary expenses which found that the system should be overhauled, said a solution could lie in politicians' remuneration.

"The more we move to just paying them income and fewer direct allowances, the less controversy there will be," he said.