The Green Party says Parliament has missed an opportunity to clamp down on anonymous donations to political parties.
MPs have approved new electoral finance legislation to govern next year's general election.
It places a $300,000 spending cap on campaigns run by lobby groups in the three months before an election.
Green Party co-leader Metiria Turei told Parliament the legislation should have gone further because the public has a right to know who is funding political parties.
As things stand, she says, the door has been left open for political corruption.