Labour housing spokesman Phil Twyford said the release from the Property Investors Federation was politically motivated and self-serving.
"It's not even a study, it's based on a few hundred self-selected landlords. It has no credibility," he said.
Twyford said Labour's policies are more likely to stabilise and reduce rents by reining in property speculation and increasing supply.
Labour says it will make renting a more stable and healthy experience.
"Labour is committed to restoring the Kiwi dream of owning your own place," said leader Jacinda Adern on September 3. "We also recognise that long-term renting has become a reality for more families but the current law creates instability and insecurity for many," she said, referring to renters being forced to more as often as once a year.
Labour will extend the 42-day landlord notice period to 90 days, limit rent increases to once a year instead of six months, ban tenants being forced to pay letting fees, and "change the law so there is the option of paying a higher bond in exchange for the ability to make a house a home by making minor alterations" Adern said this month.