National house prices hit a new high of $427,000 last month but new mortgage restrictions and a Christmas slowdown was blamed for the Auckland region prices falling $20,000.

Real Estate Institute figures showed house prices up $2000 across New Zealand from November to December but Auckland region's median price dropping from $620,000 to $600,000, Auckland City down $35,000, Rodney down $21,250, North Shore down $21,000, metropolitan Auckland down $19,000, Manukau down $8000 and Waitakere was down $7000.

Helen O'Sullivan, Reinz chief executive, said December was traditionally slower because of Christmas.

"The Auckland market is still showing strong year-on-year price growth, however over the past few months the rate of price increase has eased. Market activity is still buoyant across most of the region with good open home numbers and a continuing shortage of listings."


Auckland sales volumes were down from 2794 sales in November to 2201 last month.

The chief economist at Westpac, Dominick Stephens, blamed the Reserve Bank loan-to-value ratio measures for Auckland changes, saying latest Barfoot & Thompson data showed sub-$500,000 property sales down 26 per cent in three months but plus-$750,000 sales volumes up.

Banks must now restrict to 10 per cent of their mortgage lending the loans they provide to borrowers with a deposit of less than 20 per cent.

"The slowdown has hit low-price houses especially hard, indicating that the Reserve Bank's mortgage lending restrictions are having an impact, as are rising mortgage rates," Mr Stephens said. Data from was also showing volumes down, especially in Auckland.

He believes the housing market has entered a slowing period. Seasonally adjusted, the number of house sales per month fell 11 per cent over the three months to December, the sharpest decline since 2009.

Reinz data also showed how it takes longer to sell a house now, from 31 days in November to 32 last month.

Megan Jaffe, principal of Ray White Remuera which claims 28 per cent of sales in that area, said December was down because of the holidays. More Remuera houses were being advertised with set price tags, a trend she has noticed throughout Auckland and a big change from most of last year, she said.