While there are no exact figures showing the number of house purchases by foreigners, Real Estate Institute figures last month showed 7714 residential properties were sold. If that trend continued and around 90,000 houses were sold annually, about 8000 New Zealand houses could be going to foreigners.
Mr Alexander suggested changes. "If the housing problem is home affordability, then special generalised Auckland or national imposts such as minimum deposit rules will make things worse for the already cash/deposit-strapped group we want to be able to afford houses," he said.
"One instead will need to take buyers out of the market which are not the ones we think deserve to buy affordable housing.
"That means something like a law banning second property purchases, banning purchases by foreigners and forcing people to sell houses they own but are not occupying, perhaps because they are overseas."
Judith Taylor, previously with property specialists Australia's Property Women but now with Select Property Finder specialising in Newcastle, led a buyers' group of 40 Australians to New Zealand in 2009, saying they were interested in our cheaper houses and wanted to find out more about our market. She said yesterday that one woman bought about nine properties on that trip, and the group was enthusiastic.
She said "those who bought there were very, very happy" and had kept their places.
Mr Alexander suggested eight housing crisis solutions, saying they could "quick jump" supply but said the chances of his radical policies being adopted were between low and zero.
Maurice Williamson, Land Information Minister with responsibility for the Overseas Investment Office, has rejected the concept of a foreign buyer register. But the office does not have jurisdiction over most house sales and only handles $100 million-plus property deals, those involving sensitive land such as seaside or lakefront or fishing quotas.
David Whitburn, Auckland Property Investors Association president, agreed foreigners should be discouraged from buying here - not by being banned, but by being charged more.
"If you are not a permanent resident or citizen, there should be a strong investigation into charging a stamp duty charged on your purchase," he said.
"Perhaps something like 4 per cent of the purchase price.
"We cannot risk offending our major trading partners, so whatever moves are made cannot be too drastic.
"Foreign purchasers are only a minor reason for the strongly rising Auckland market," Mr Whitburn said.
"Two decades of inept local and central government policies have meant uncertainty for developers with high development costs.
"We have a continuation of very strong population growth in Auckland. The Auckland market is likely to keep rising until the supply side is sorted," Mr Whitburn said.
Peter Thompson, Barfoot & Thompson managing director, said only a small proportion of auction bidders at his firm's Shortland St rooms were Asian and many of those could be residents or descendants of New Zealanders for many generations.
But Ian Thornhill, a Barfoot agent, raised concerns about the situation last year, commenting after an Epsom deal when a Chinese investor bought a house then left it empty.
Alistair Helm, a real estate commentator, has singled out New Zealand as one of the few countries in the world not to impose a stamp duty in the form of a tax on a property purchase, that makes no capital gains taxation on property sales and that has no restriction on foreign ownership outside of the rules of the Overseas Investment Office.