Provincial New Zealand is paying for Auckland's overheated housing market, the Auckland Chamber of Commerce says.

The head of the chamber, Michael Barnett, said his organisation was worried the Reserve Bank's new requirement for a 20 per cent minimum deposit on most new mortgage loans was beginning to have unintended effects.

One was that by taking first-home buyers out of the market, developers might be encouraged to continue building expensive homes, resulting in fewer affordable new homes, he said.

His other concern was that the rest of New Zealand was being "unfairly penalised" with measures for Auckland's overheated housing market.

"This is reinforced in the NZIER's recent release showing Auckland's real house prices are up 15 per cent on 2007 while for the rest of New Zealand they are down by 25 per cent," he said.

He called on the Reserve Bank to come up with an Auckland-specific policy.

"With Auckland 35 per cent of the New Zealand economy and the dominant player, it is time that policy designers and decision-makers in Wellington took a more innovative and realistic stance in their approach to addressing issues."

However, BNZ chief economist Tony Alexander said there was still too little data to tell what impacts the limits on high loan-to-value ratio (LVR) lending were having.

No-one knew whether first-home buyers in the regions were being harder hit.

"I think people are just feeling it because many of the regions have yet to stage a decent recovery."

Alexander said there might be some validity to Barnett's concerns about developers being swayed away from affordable housing, but it was not clear whether they were building much beforehand.

"The whole thing about the LVR changes is completely subjective at the moment," he said.

"We have evidence of the number of loans being advanced, they're falling away 10 to 15 per cent on a year earlier. But all the other indicators I think are a bit all over the place."

Real Estate Institute chief executive Helen O'Sullivan said it was true house prices outside Auckland and Christchurch were "a very different picture". But her data were not as dramatic as Barnett's, which were adjusted.

Without adjusting for inflation, her figures showed the national median house prices, excluding Auckland, were 5.4 per cent above the market peak.

If Canterbury was excluded as well, the median house price was virtually unchanged since 2007 - up just 0.9 per cent.