Both Ardern and Peters faced media after today's Cabinet meeting, with Peters referencing Moses and Zimbabwe in explaining why the longer document wouldn't be released, and the Prime Minister preferring to call it a collection of notes.

"Of course we made notes during the course of those [coalition] discussions, including further areas that we may undertake some work. Those things that we formally signed up to, they made it into the coalition agreement [publicly released]," Ardern said.

"There are other areas that we may explore together, that may be found to be unworkable, that may be found to just be fiscally irresponsible, that may never be progressed … at the moment that we see some benefit and that it is something that we will progress, that is the point at which it will be made public.

"We are certainly not leaving it in the shadows … at the time that those elements are worked through and found to be workable options and ideas, then they will be released."

Pressed on why Peters said the document would be released and not elements as policy work progressed, Peters took the lead.

"I mean Moses came down from the mountain, he only had 10 commandments, right? But there's a lot in the Old Testament as well. Get it?

"I'm only here because the Prime Minister asked me to be here. This is not Zimbabwe all over again."

Earlier, Ardern's office declined an Official Information Act (OIA) request by Newsroom, saying the Prime Minister does not hold such official information.

The office referred to Section 2 of the Act, saying official information is only that held by a Minister of the Crown in his official capacity.

National leader Bill English said Ardern needed to release the "secret agreement", which "goes to the very heart of the formation of the new Government".

"It is unacceptable for the Prime Minister to claim it's not public information. It is and the public deserves to know how the new coalition, and therefore the country, will be run," English said.

"This is not the openness and accountability promised by Jacinda Ardern and Winston Peters and enshrined in the public version of their coalition agreement. It's certainly not them living up to their promise to 'strengthen New Zealand's democracy by increasing public participation, openness, and transparency around official information'."

The refusal to release the document comes as National attacks Labour over what it says is a lack of transparency over answers to written questions, with Labour accusing the Opposition of time-wasting tactics.

Opposition MPs can lodge written questions to ministers, with the answers then published online. Since Labour came to power National has lodged thousands, with many asking what meetings a minister held on a specific date.

National says it is doing so because Labour will not provide proper answers, but Labour's Leader of the House Chris Hipkins has labelled the questions the equivalent of Parliamentary spam mail.

Briefings to Incoming Ministers (BIMS) have not yet been released. That would happen next week, Ardern said today.