Parliament's environment watchdog has written to ACT deputy leader Brooke van Velden to say she is sharing misinformation about his findings on the oil and gas ban.
Parliamentary Commissioner Simon Upton says van Velden was "incorrect and misleading" when she said on TVNZ's Breakfast show that the commissioner has concluded the ban on offshore exploration for oil and gas would likely "increase global emissions".
Upton's letter notes a similar comment appears in ACT Party energy policy.
Despite the letter being sent last week, the claim was still on the party's website Thursday morning.
Upton said in his letter the claims were incorrect and misleading because his report on the oil and gas exploration ban concluded "there is no firm basis for claiming that it will increase global emissions".
"I most definitely did not say that the ban would increase global emissions," the letter said.
The ACT Party said van Velden was talking about the closure of methanol-making facilities when she quoted the Parliamentary Commissioner for the Environment.
A statement from the party, attributed to van Velden, said Upton's report on the offshore exploration ban noted the risk of premature closure of gas-fired methanol-making facilities, and this could drive production overseas to coal-fired factories.
ACT has been critical of the former government for not conducting a thorough analysis of the costs and benefits of banning offshore oil and gas exploration.
The commissioner's report did express concerns that the impacts of the ban were not fully analysed.
Overturning the ban was a policy of both ACT and National, and the new government has been criticised for it by green groups at the COP28 climate summit in Dubai this week.
Upton's letter ends with a suggestion that, after criticising the Labour-led government for not making a careful analysis of the costs and benefits of the ban, "It would create an excellent precedent if your decision to lift the ban followed a thorough analysis of the costs and benefits of such a step".
"Five years have passed since the imposition of the ban and much has changed since then."
ACT said it could comment on whether it would push for this "as decisions have not yet been made on that process".