The Banker's Association says first-home buyers are likely to be the most affected if the Reserve Bank introduces restrictions on low-deposit home loans.
Under the proposed changes, the Reserve Bank would require trading banks to increase their loan-to-value ratios which would restrict mortgage lending on low-deposit loans.
Banker's Association's chief executive Kirk Hope said the change would probably affect first-home buyers disproportionately, because they make up a higher proportion of those coming into the market with high loans and a deposit of less than 20%.
In June, Reserve Bank deputy governor Grant Spencer said it was seriously considering restricting low-deposit loans, rather than raising interest rates. He said the rate of new mortgage approvals and loans had been growing and were now comparable with peak levels before the global financial crisis in 2008.
The Reserve Bank won't yet comment about when or if announcements will be made.
However Labour's housing spokesperson Phil Twyford said on Tuesday he has been made aware the restrictions are imminent. "This is a real kick in the teeth actually for first-home buyers. It's going to lock out thousands of low-to-middle income first-home buyers and actually give an advantage to speculators."
Mr Twyford said Labour would apply an interim exception to the restrictions for first-home buyers while a scheme to build more affordable homes is carried out.
Massey University's head of banking studies, David Tripe, said a blanket restriction would be unfair, as Auckland properties were usually more costly than houses in smaller regions.
Mr Tripe said the changes could lead to prices falling in the regions, and less spending, which is not healthy for the economy.
BNZ economist Doug Steele said if the central bank won't lift interest rates and did not bring in the restrictions, house prices would continue to rise.