The Labour Party says the likelihood of lower insurance premiums under proposed changes to the Earthquake Commission Act is slim, despite the Government saying it could happen.
The Green Party, meanwhile, said a proposal that land-only damage would not be covered could be too restrictive.
A review of the act recommends that the commission scrap contents insurance and some land cover for natural disasters but double the cap on building cover to $200,000. The change is proposed to make sure the insurance scheme remains sustainable.
Canterbury Earthquake Recovery Minister Gerry Brownlee said he expected the changes to have a modest impact on insurance premiums.
"We believe the proposals, if implemented, will better position homeowners, EQC and private insurers to plan for and recover from future natural disasters."
Labour's earthquake recovery spokesperson Clayton Cosgrove said lifting the rebuild cap could reduce the friction and overlap between EQC and private insurers. However, he was less optimistic about lower insurance premiums.
"We've never seen insurance come down in cost, we've only ever seen it go up. It never went down prior to the major Christchurch earthquake."
He said if private insurers were asked to do more, they would want to charge more.
Concerns about land insurance restrictions
The Green Party said the idea of only insuring land that was impossible to rebuild on after a natural disaster could be too restrictive.
Today, Mr Brownlee said earthquake land cover would only apply to situations where homes could not be rebuilt on their original site and owners were forced to buy elsewhere.
If the change is implemented, EQC would no longer cover land damage that has not affected a house on the property.
The Greens' Christchurch spokesperson, Eugenie Sage, said many people would have been left high and dry after the Canterbury earthquakes if that had been the case at the time.
"(It) potentially penalises a lot of people in situations like Flockton Basin in Christchurch, where earthquakes have damaged the land, increased the vulnerability to flooding - and who is then to compensate home owners for that increased risk?"
But Ms Sage agreed with the recommendation that EQC not cover contents in a natural disaster.