An individual body needs to be in charge of implementing and controlling rules surrounding the complicated expenses system for MPs, an expert on political corruption says.
New Zealand is one of the least corrupt nations in the world, but MPs are in danger of maintaining a perception of impropriety by insisting on controlling the rules surrounding expenses themselves, corruption watchdog Transparency International founder Jeremy Pope told NZPA.
Recent reports revealed seven MPs had bought properties they used as out-of-Wellington offices, billing the taxpayer for the rent.
Some were owned in the MPs' own names, while others were held through superannuation funds or companies.
The loophole allowed them to walk away with substantial capital gains.
The Auditor-General's office, already investigating a complaint about the accommodation allowance paid to Finance Minister Bill English, is considering whether to expand its inquiry into MPs' accommodation allowances.
Mr English paid back $12,000 and stopped claiming an out-of-town allowance following publicity he was claiming the allowance but lived mostly in Wellington.
In much of the world the politicians "rob the public purse blind," Mr Pope said.
"Now New Zealand can be extremely grateful we don't fall into that category at all.
"The present debate needs to be informed that we are goodies and not baddies in all of this."
But the real problem lay in the absence of accountability, he said.
"Politicians are seen as being accountable to themselves.
"They have a system that they worked out for themselves and it is administered by the Speaker who is one of themselves."
While that system could work perfectly well, the public could focus on no independent element in place to keep accountability in check, he said.
Former auditor-general David Macdonald, a member of Transparency International, wrote a report, as auditor-general, that argued strongly that questions about all MPs' allowances should be handled by an independent agent, Mr Pope said.
"The politicians would do well to look again at his recommendations, because they accepted a number of his recommendations, but not some of the key ones, and that was one that was key."
If the allowances were handled separately, that would act as protection for the politicians, Mr Pope said.
"Whether (corruption) is happening or not, it's important that the issue is really put behind the politicians so they can get on with running the country.
"I think simply to wait for the controversies to die down and feel they've gone away - they will only come back again because that is the nature of these things."
The MPs might be playing by the rules, but that was no reason not to change the system, Mr Pope said.