Prime Minister John Key says there's a risk that new disclosure rules for MPs' travel expenses will undo recent moves towards more transparency.
The Speaker of the House has introduced new rules to keep secret individual MPs' use of travel perks, but will instead publish the total rebate paid out to all MPs.
The Speaker, Lockwood Smith, says MPs have money deducted from their salary to cover the cost of the rebate, and so he considers that they have paid for it out of their own private funds.
Mr Key says he understands the logic of Dr Smith's decision, but it might appear to the public that there is less openness.
However Mr Key says it's the Speaker's call, and he has no rights to overrule that.
The Green Party is calling for an independent review of MPs' salaries and expenses because it says current system is messy and open to abuse.
Green Party co-leader Metiria Turei says there's not enough transparency in the system that allows MPs to use allowances and expenses for personal purposes.
She says Lockwood Smith is just fiddling at the edges by making public the total amount spent by MPs on private travel, but ignoring calls for an independent revamp of the system.
Dr Smith says he's asking the Remuneration Authority to publish the way it sets an MPs' total salary package. He says MPs may decide in the future they want to change the way they're paid.