Home affordability in New Zealand cities deteriorated last year, with the average metropolitan house costing 5.3 times the average income, up from 5.2 last year, sending them further up the "severely unaffordable" index.
The 2013 9th Annual Demographia International Housing Affordability Survey covers 337 urban markets in the United States, Britain, Canada, Australia, New Zealand, Ireland and Hong Kong.
It uses a "median multiple", where the median house price is divided by the gross annual median household income.
In affordable and normal housing markets, house prices do not exceed 3.0 times annual household incomes.
The survey rates affordability as severely unaffordable at 5.1 and over, seriously unaffordable at 4.1 to 5.0 and moderately unaffordable at 3.1 to 4.0
A level over 5.1 indicates there are political and regulatory impediments to the supply of new housing that need to be dealt with, the survey authors said.
Auckland is the least affordable market, with a median multiple of 6.7.
Christchurch (6.6), Tauranga-Western Bay of Plenty (5.9), Wellington (5.4) and Dunedin (5.1) also rate as severely unaffordable.
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Three metropolitan areas were seriously unaffordable - Palmerston North (4.4), Napier-Hastings (4.5) and Hamilton (4.7).
New Zealand had no affordable markets and no moderately unaffordable markets, the survey showed.
Finance Minister Bill English tackles the issue of affordable housing in the study's introduction, saying the Government was focusing on four structural impediments to restore affordable housing in New Zealand - land supply, infrastructure, process and construction costs.
He told Radio New Zealand today that the Government was "focused on working with councils" to make housing more affordable.
He said Treasury forecasts showed house prices could continue rising this year but that a lift in supply could see prices level off after that.
Internationally, housing affordability was little changed in 2012, with the most affordable markets being in the United States, Canada and Ireland.
Britain, Australia and New Zealand continue to experience pervasive unaffordability, while the least affordable market is Hong Kong.
''Houses in New Zealand are now nearly 80 per cent more expensive than the historic affordability housing norm of 3.0, last experienced in the 1990s,'' the survey said.