New Zealand house price inflation continues to be dominated by Auckland where housing supply isn't meeting demand.

Auckland’s median house price jumped 13 per cent to $NZ720,000 ($A707,478) in March, compared with the year-earlier month, outstripping an eight per cent rise in the national median price over the same period to $NZ475,000, the Real Estate Institute said in a statement.

Excluding Auckland, the national median price increased 1.4 per cent to $NZ350,000 compared with the year earlier, unchanged from February, the agency said.

“The movement in the national median price is almost entirely an Auckland effect,” said REINZ chief executive Colleen Milne.

“The underlying demand pressures remain and supply continues to be restrained by low numbers of new listings.”

The Reserve Bank estimates Auckland has a shortfall of between 15,000 and 20,000 properties to meet population growth as the country experiences record migration.  Some 8,803 residential properties were sold in March, 20 per cent ahead of the year earlier and the highest level since 2007, REINZ said.

Auckland March sales volumes increased 21 per cent from the year earlier month and were 56 per cent ahead of February, the agency said.

Auckland had a record number of auction sales in March, accounting for 78 per cent of sales, and had a spike in the number of house sales worth more than $NZ1 million, which helped push up Auckland median prices, it said.

Houses took a median 32 days to sell last month, one day fewer than March last year.

The REINZ stratified housing price index, which strips out variations in the mix of high and low-values homes sold, rose 9.5 per cent to a record 4,340.9.

The Auckland index gained 20 per cent to a record, the Christchurch index rose five per cent and the Wellington index advanced 3.8 per cent.