New data indicating Auckland house prices have rocketed by $20,000 in just a month has sparked fresh opposition calls for a register of foreign house buyers and curbs on their purchases.
Auckland properties sold by the city's biggest agency, Barfoot & Thompson, hit a new all-time high of $756,909, up $20,671 in just 30 days.
Labour Leader Andrew Little said the data showed "a major problem" in the Auckland housing market.
Responding to a media question about a Chinese real estate website that currently lists 8500 New Zealand properties, Mr Little said: "The problem we have I think particularly for first home buyers and especially in Auckland is that they're being out bid and outpriced by offshore buyers, people who aren't even living here but want property here".
"The Government has to do something about it. The Australians have had a look at their programme of putting restrictions on offshore buyers, we should be doing the same thing.
"They've clearly got a programme that is effective... and it's time the New Zealand Government looked at something here.
"They know there is a problem they've just chosen to do nothing about it."
Mr Little said a register of foreign buyers would help clarify the extent of the problem before restrictions could be implemented.
Prime Minister John Key said he was unsure how accurate or reflective of the entire Auckland market Barfoot & Thompson's data was.
"Certainly the Auckland property market is strong and that's one of the reasons the Government's got a programme of fundamentally building more houses.
"It's also probably a sign of confidence in the economy post the National led Government."
Asked about Australia's restrictions which allow foreigners to buy only new homes, Mr Key said that had seen "an awful lot of people buying houses and actually their house prices have been rising faster than ours".
He said a register of foreign buyers was "not our number one focus of attention".
The clearest indication of offshore ownership of New Zealand houses was IRD data on foreign tax returns related to rental property.
"They've been very consistent over the last five or ten years, so it's not showing that there's a dramatic increase in foreign buyers at this point. I think sometimes people confuse someone that is Chinese of another ethnicity and think of them as foreigner but they may well be a New Zealand resident or citizen."
Mr Key said his Government hadn't taken advice at this point on whether a register of foreign buyers was worthwhile.
"I can't 100 per cent rule that out but really our big focus of attention is fixing the supply side."