A report the government tried to keep secret says its approach to social and affordable housing is fragmented and lacks a robust plan.
The external review of the Social Housing Reform Programme noted that, in Auckland, three ministers and four government agencies lacked an overall plan to boost housing supply.
It found the government needed to "increase the overall supply of housing, particularly in Auckland".
The 135-page review, done for Treasury, was finished in December 2015.
Last September, then-Minister of Social Housing Paula Bennett refused to release the report to RNZ.
She said to do so would "prejudice the quality of information received" and "the wider public interest of effective government would not be served".
RNZ obtained the report only after an appeal to the Ombudsman under the Official Information Act.
In the review, consultants Leonie Freeman and Michael Miles looked at the government's aim to provide social housing largely by paying providers.
They found the target of providing 65,000 income-related rent subsidy places by mid-next year lacked a robust plan. They noted problems with monitoring progress.
The report expressed concern about progress in clarifying Housing New Zealand's role in the new community housing market.
"Decisions are yet to be taken on the Boston Consulting Group review of HNZC's ongoing role and structure - these decisions are critical."
The review recommended a Social Housing Programme office, which would answer to key ministers and establish a single agency to manage property sales and the redevelopment of Crown land.
Withholding the report for six months allowed it to be released with a letter from the Ministry of Social Development's deputy chief executive for social housing Scott Gallacher, which outlined subsequent progress.
It said the ministry took up the recommendation to become a more "intelligent social housing purchaser", by buying support services as well as bricks and mortar.
"MSD issued its latest purchasing strategy, which includes its plan to purchase over 6,400 additional social housing places by June 2020," Mr Gallacher's letter said.
The Community Housing Association said there had been progress in social housing, although a longer term plan was needed.
"We need to get the production machine going so we can deliver at 1000 new social and affordable housing places every year," association director Scott Figenshow said.
Mr Figenshow said there had been little progress in boosting the supply of affordable housing, and creating new schemes to help people secure their own homes.
The report found, in order to successfully deliver social housing, the government needed to "increase the overall supply of housing, particularly in Auckland, by facilitating the development and redevelopment of surplus Crown and under-utilised Housing New Zealand land."
It called for a 10-year plan for new homes on Crown and HNZ land, including a specified split between social, affordable and mixed tenure developments.
"We can do this, but only taking a fraction of the recommendations in a report like this doesn't do it," Mr Figenshow said.
"Just picking a small set of recommendations from just one of the planks is not enough," he said.