Information about the harm caused by the SkyCity convention centre deal was withheld because it was considered commercially sensitive to the casino firm, official papers show.
The papers show the office of Minister Steven Joyce sought greater disclosure on the harm caused by gambling than officials made public.
"The Harm stuff looks a bit light. Is there no more on that?" the minister's office was quoted as asking, according to papers released under the Official Information Act.
They stemmed from the officials' efforts to proactively release information relating to the controversial cash-for-pokies deal, which will involve the Government changing the law in return for SkyCity building a $400 million International Convention Centre next to its Auckland casino. The law change will let the casino increase the opportunities to gamble.
The Herald sought the officials' deliberations, which included consultation with Mr Joyce's office over what was being released.
His staff raised questions over the amount of information withheld.
"Why so much withheld? What is that mostly about?" they asked the Ministry of Business, Industry and Employment.
The answer was withheld from release.
When asked specifically about social harm, the officials said: "Harm minimisation material is generally being withheld for the following reasons" before listing commercial interests as the lead reason, along with legal advice and the freedom of officials to express opinions.
"If it was assessed that any of the above grounds do not actually apply, there would be significantly more material to release." The officials said the release of information would need to be agreed by all parties "which should be possible now negotiations have concluded - though SkyCity as a private enterprise will likely take a different view".
Green Party co-leader Metiria Turei said it raised questions over what SkyCity knew about the harm its casino caused which it did not want made public.
The legislation which would change the law and allow greater gambling at SkyCity is expected back in Parliament this week.