KiwiRail reversed a decision to make a report public after Transport Minister Simon Bridges' office raised concerns with one of its executives.
New emails obtained by RNZ reveal their back-and-forth over how to respond to a request for official information about a proposed rail freight line between Wiri and Westfield, in Auckland.
New Zealand First last week revealed Mr Bridges' staff had repeatedly urged KiwiRail not to release the business case, arguing it could form part of a future budget bid.
The new correspondence shows the state-owned company eventually conceded after Mr Bridges' officials escalated the matter to one of KiwiRail's executives.
On 6 June, KiwiRail reversed its initial decision to release the document in full and instead decided to withhold it altogether.
It changed its draft response to read: "Disclosing the document could inhibit KiwiRail from carrying out, without prejudice, future negotiations."
Mr Bridges' staff immediately replied: "The Office is supportive of this response."
However just days earlier, on 1 June, KiwiRail said its legal advice was that releasing the report "would be unlikely to prejudice our negotiations".
It said it would therefore struggle to justify holding it back.
The next day, Mr Bridges' staff contacted a member of KiwiRail's executive, Todd Moyle, saying they were "extremely uncomfortable" with the document being released.
Eventually, just hours after KiwiRail conceded, New Zealand First leader Winston Peters raised the matter in Parliament.
After three days of media scrutiny and questions, KiwiRail changed its mind again, telling the minister's office it now intended to release the document publicly.
The rail company yesterday published the business case online, with several passages redacted.
Mr Bridges has previously defended his officials' actions, saying they were right to push back against Kiwirail's initial view the report should be released.
He said the document was a very early draft and materially wrong in many respects.
The Ombudsman is to properly investigate the case after New Zealand First formally requested it do so.
Chief Ombudsman Peter Boshier this week wrote to Prime Minister Bill English, asking for an assurance ministers are following the law when dealing with official information.
- 29 May - KiwiRail tells Mr Bridges' staff it intends to release the report.
- 30 May - Mr Bridges' staff "strongly recommend" the report be withheld, arguing it could form part of a future budget bid.
- 31 May - KiwiRail consults its legal team.
- 1 June - KiwiRail tells Mr Bridges' staff it would to "struggle to justify non-release". KiwiRail says its legal advice is that releasing the report "would be unlikely to prejudice our negotiations".
- 2 June - Mr Bridges' staff escalate the matter to KiwiRail's executive and say they're "extremely uncomfortable" with the report being released.
- 6 June 1.22pm - KiwiRail revises its response, this time withholding the report in full. "Disclosing the document could inhibit KiwiRail from carrying out, without prejudice, future negotiations."
- 6 June 1.25pm - Mr Bridges' staff replies: "The Office is supportive of this response."
- 6 June 3.02pm - Winston Peters raises the matter in Parliament and releases an email trail between Mr Bridges' staff and KiwiRail.
- 7 June - Mr Bridges declines to be interviewed on RNZ. In a statement, he says his office had only offered a view and it was up to KiwiRail whether they released information.
- 8 June - Mr Bridges defends his officials' actions and says they were right.
- 9 June - KiwiRail again revises its draft response and tells Mr Bridges' office it now intends to release the document publicly.
- 13 June - Chief Ombudsman writes to the Prime Minister, asking for an assurance ministers aren't flouting the OIA. New Zealand First formally requests the Ombudsman investigate.
- 15 June - KiwiRail releases the document with redactions.