Barfoot and Thompson suspect Labour's leaked house sales data came from them
Real estate company Barfoot and Thompson "assumes" it was their Auckland house sales information that was leaked to Labour and has launched an investigation to ferret out the data thief.
Meanwhile, Labour leader Andrew Little has rejected criticism that the data - which identified buyers as Chinese from their surname - was "an exercise in unveiled racism."
On Saturday Labour's Phil Twyford released figures based on house sales data from 3922 Auckland sales from February to April.
He then extrapolated from the list's Asian-sounding names that Chinese buyers accounted for 39.5 per cent of buyers compared to the 9 per cent of Auckland's population recorded as being ethnically Chinese in the latest census.
Twyford refused to say where the data had come from but Barfoot and Thompson chief executive Wendy Alexander said the company suspected it had come from them due to the volume of sales involved.
Barfoot claims to sell about one-third of the houses in Auckland and the data was said to represent about 45 per cent of the sales in the period.
Alexander said the company had started an investigation "to see if it was leaked and by whom".
Sales data was shared within the company and it was possible to access the list of buyers' names, she said.
Property Institute chief executive Ashley Church said Twyford's research was "reprehensible" and "an exercise in unveiled racism".
Church said Twyford's methodology did not differentiate whether the buyer lived in New Zealand or was an investor based in China.
He said while Twyford's claims that overseas investors were skewing the market could turn out to be correct, that conclusion should be based on hard data and facts "and the race of the buyer shouldn't be a factor".
"We might be surprised to learn who the major investors really are. Work done by the Overseas Investment Office, in 2012, suggested that the biggest buyers were Americans, Brits, Canadians and Aussies – with the Chinese a long way behind".
Labour leader Andrew Little said he had backed the use of the data, and rejected claims it was racially motivated.
"We got this data, it was leaked to us, and we had to decide what to do, do we sit on it, or do we use it to highlight a serious issue?"
We made the call to show what's happening in the Auckland property market. We knew that some quarters would say it was racist, but I reject that."
Not enough was being done to curb overseas-based property investors, Little said.
Under Labour non-residents would face restrictions on the purchase of residential property.
They could only buy property if they intended to live in New Zealand permanently, or if the purchase added to the existing housing stock, for example
by building a new house.
ACT's Epsom MP David Seymour said he did not dispute Twyford's figures but focusing on who was buying the houses missed the point.
He said his own anecdotal evidence was that there were a lot of Chinese people showing up to buy houses in Auckland.
"Everything Phil Twyford says is probably true. If you just focus on that, people will get angry with each-other."
Seymour said increasing supply on the rural fringes of Auckland was the best way to alleviate the price pressure.
"If you have a city that has very restrictive planning rules, you will get unaffordable housing."
Seymour said London, Vancouver and Sydney also had unaffordable housing and all those places had capital gains taxes.
Seymour suggested Labour had picked the issue to try and galvanise "soft-centre voters" and regain those lost to New Zealand First in the last election.