Prime Minister John Key is warning investors chasing gains in the Auckland housing market they could face a "nasty surprise" as he appeared to tip a cooling of booming price increases.

Million-dollar properties in Hawke's Bay are in hot demand, as interest from national and international buyers strengthens, a real estate agent says. New Zealand Sotheby's International Realty Hawke's Bay managing director Fraser Holland said despite short working days during the holiday period, sales had not slowed.

New Zealand banks are moving quickly to lower mortgage lending rates after the Reserve Bank of New Zealand cut its official interest rates. Fletcher Building has completed the $A150 million sale of Rocla Quarry Products assets to Hanson Construction Materials following clearance from the Australian Competition Commission and the Foreign Investment Review Board.

Building consents for new homes in New Zealand totalled 27,132 last year and construction value is now topping $NZ1 billion ($A914.20 million) a month, the government says.

A new survey ranks Auckland as the fourth-least affordable place in the world to buy a house. In the latest Demographia Housing Affordability survey released on Monday, the city jumped from ninth to equal fourth in the global rankings in the year to sit alongside Melbourne and San Jose.

Private banking for the very wealthy is booming as ageing business owners cash up. Donna Nicolof, BNZ's head of wealth and private banking, says BNZ's private bank had doubled its funds under management in the past three years.

The New Zealand Property Council has waded into the debate about the unaffordability of housing in Auckland, saying apartments are pre-selling in the city for more than $NZ800,000 ($A752,000) each.

New Zealand property values rose 14 per cent in 2015, with the annual pace slowing from a peak in November, as regulatory curbs imposed by the government and central bank took the steam out of the Auckland market, according to state-owned valuer Quotable Value.

A Chinese company is lining up against Australian social housing provider Horizon Housing in the sell-off of state houses in New Zealand.

The number of houses listed for sale in Auckland dropped to its lowest number in 20 years at the end of December, the city's biggest real estate agency says.