Private member's bill seeks to have publicly owned ports covered by the Official Information Act.
Labour will cite secrecy over the costs of Auckland's marathon waterfront dispute as a reason to pass legislation due before Parliament this week to open port companies to public scrutiny.
That follows failure by Auckland Council members at a committee meeting on Thursday to discover from their organisation's investment arm how much the unresolved dispute has cost ratepayers.
Although Auckland Council Investments owns the region's port on behalf of the council, chief executive Gary Swift told the accountability and performance committee he did not consider such information appropriate for his organisation to ask for in its governance role.
Despite that, he said the agency had not seen in financial reports from the port company any indications that costs were at such a level as to cause it concern as a shareholder.
That prompted councillor Mike Lee to remind him of "an old maxim - if you can't count it, if you can't measure it, you can't manage it".
Labour's industrial relations spokeswoman Darien Fenton said ratepayers deserved to know what was going on with their assets.
"ACIL is treating the democratically elected council with contempt," she said.
Ms Fenton said Parliament would have an opportunity to remedy the situation on Wednesday, when the first reading is due of a private member's bill she is sponsoring to open publicly owned ports to the Official Information Act.
Councillor Cathy Casey questioned the sincerity of Mr Swift's stated attempt to draw a distinction between governance and management of the port company, after reading out an email he sent in December to the company's communications manager.
In it, Mr Swift said it was critical for all "key players" to be kept informed and for politicians to be confident the dispute was being overseen not just by the company's board but also by ACIL.
"The last thing we want is political interference," he wrote in his email to the manager, Catherine Etheredge, who left the company soon after.
"If they sense that ACIL is not on top of what's happening, they may interfere and it may not go the way we want."
Mr Swift denied interfering in the company's management of the dispute, saying the email was an attempt to keep a focus on the commercial return which the council had sought from the port.
Asked by Dr Casey what he meant in saying "it may not go the way we want", he said the reference was to the council's requirement for the port company to achieve a 12 per cent on its shareholders' equity.
The dispute remains in the hands of an Employment Relations Authority facilitator.
Mr Swift told the council in April that it was likely to cost ratepayers about $8 million in reduced dividends.
Some companies have complained to ExportNZ of losing up to $250,000 because of the dispute.
* The cost so far: Nine strikes, two lockouts and at least $8 million in reduced dividends to Auckland Council.
* Where it stands: A truce was reached in late March allowing 235 workers back to the port. A threat to outsource jobs was lifted.
* However, the issues remain to be resolved before an Employment Relations Authority facilitator.