Auckland Council's solution for the city's housing crisis has been running for four years but it still cannot say how many affordable homes have been built.
The council has set up more than 150 Special Housing Areas (SHAs) with the government, under the Housing Accord, in order to fast-track building tens of thousands of new homes.
Under the deal at least 10 percent of large developments have to have cheaper homes for first-home buyers on modest incomes.
But the council said it had no single system for monitoring exactly how many had been built and sold.
Building and Construction Minister Nick Smith said when the government owned the land it could determine prices but in private subdivisions it never had.
Its programme with the Auckland Housing Accord had been to unlock land to increase the supply of housing and that was succeeding, he said.
"We consented more houses in the month of May than in any year in 40 years."
Dr Smith said the government's position was that regulating house prices through the Resource Management Act was never going to succeed, and requirements for statutory declarations were dropped when the Unitary Plan superseded the accord in October, because the evidence was those mechanisms didn't work.
He pointed to the Massey Home Affordability Survey (PDF, 720KB), which showed some improvement in the level of average income required to service a mortgage in the city.
Listen to RNZ's housing reporter, Sharon Brettkelly, talk to Morning Report about the story.