A senior lecturer in banking says a potential mortgage interest rate rise to 8% percent would be a burden on homeowners.
In a newspaper opinion piece published on Thursday, Reserve Bank Governor Graeme Wheeler said if new lending restrictions don't reduce house prices, it could mean the benchmark interest rate rise.
The Reserve Bank says the Official Cash Rate could increase by 2% from 2014 to the beginning of 2016, which could mean interest rates on first mortgages of 7 - 8%.
New lending rules set by the central bank mean no more than 10% of a bank's mortgage lending can be to people with deposits of less than 20%.
Massey University lecturer Claire Matthews says bigger loans and a higher interest rate would increase repayments, making things more difficult for mortgage holders.
"As well as the problems around the higher deposit requirements, they're also going to have higher repayments they're going to have to cope with on top of that, and that means they need higher incomes to manage."
Dr Matthews says people who have had a mortgage for a long time would have started with a higher interest rate so would be better prepared to cope with a rise.
ANZ chief economist Cameron Bagrie says new restrictive lending rules are the lesser of two evils, as the alternative is raising interest rates which would hurt both home buyers and exporters.
Regional restrictions urged
The Professional Advisors Association, which incorporates the former Mortgage Brokers' Association, says there should be regional mortgage restrictions applying only to big cities.
Board member Karen Mooney, a mortgage adviser in Blenheim, says regional restrictions would not be difficult to manage. She says restrictions applying across the board are not good for the economy.
But Bankers Association chief executive Kirk Hope says it would be too difficult to administer. He says banks are already trying to work through the restrictions on a national level and regional ones would stretch them.
Agency puts price rise down to mortgage rules
The country's largest real estate agency believes the spike in the price of the Auckland properties it sold during September was due to buyers willing to pay more to get ahead of the more restrictive lending rules.
Harcourts says there was a 7.7% price increase in September over August.
Chief executive Hayden Duncan says its average sale is now $640,739 - the highest average this year. "Over the last month the only thing that has been out of the ordinary ... is the changes to the LVR (loan-to-value ratio) coming into force on the first of this month."
However another major real estate agency, Barfoot and Thompson, says it has recorded only a slight rise in house prices during September.
The Real Estate Institute says it will be another month before a clearer picture emerges of what impact the new lending rules are having on the market.