The government and the Reserve Bank are warning property speculators they're taking a big risk if they think Auckland house prices are going to keep on rising.
Finance Minister Bill English says the supply of new houses is picking up speed.
"People have to understand this - the government and the council are determined to see more supply," he said today.
"We know from markets around the world that any market that rises as fast as Auckland's ends up falling."
He's using Christchurch as an example of that.
"Christchurch prices are falling, very gently, after a period of extreme shortage," he said on Radio New Zealand.
Reserve Bank governor Graeme Wheeler yesterday told parliament's finance and expenditure committee the Auckland market was in dangerous territory.
Two years ago property speculators made up 33 percent of the market and now the figure was 41 percent, he said.
"The house price to income ratio for Auckland is nine, it's twice that for the rest of the country," he said.
"A ratio of nine puts it in the top 10 most expensive cities in the world - this is just dangerous territory."
In parliament, Economic Development Minister Steven Joyce said buyers needed to understand that interest rates weren't going to stay low for ever.
"They generally pay off their houses over a very long time," he said.
"It's important for people to understand that you can pay too much for a house."
The Greens say rampant property speculation is the government's fault, because it's allowing to happen.
"It could tackle it with a proper capital gains tax and restrictions on overseas investors, but it's choosing not to," said finance spokeswoman Julie Anne Genter.
"Now it's a problem that's putting the whole economy at risk from a sharp correction."
Labour's housing spokesman, Phil Twyford, says Mr English should behave like a finance minister, not a financial adviser.
"He's warning Aucklanders about the housing market instead of fixing it," he said.
"Mr English has delegated the housing crisis to the Reserve Bank and is now just a spectator on the economy."