Filmmakers Sir Peter Jackson and Dame Fran Walsh have threatened high court action over decisions about the contentious Shelly Bay development in Wellington.
RNZ has obtained the letter sent to the chief executive of Wellington City Council and councillors on Friday over the $500 million development.
It has asked for confirmation by Friday that the 2017 vote to sell and lease the land at Shelly Bay would be put back before the council, and that the council would take no further action until there was an agreement.
The letter states that any further work on the proposed development, without the council's full reconsideration of it, would be done on a knowingly false foundation to which the council based its 2017 decision.
It also reads that to continue with the development, without the council reconsidering it, would make it open to urgent judicial review.
In a statement, Wellington Mayor Andy Foster said there had been no change in the situation regarding the development of Shelly Bay, and the matter would come back to the council in due course.
"The council has agreed, in principle, to sell and lease small portions of its own land, following preparation of a commercial agreement," Foster said.
"The terms and conditions of that agreement are being worked on now by senior council officers, so that it has all the relevant information when it is reported back to the council later in the year. There is a long way to go on those terms and conditions."
At that stage, the council would then make a final decision, he said.
"With the council's full knowledge and support, our Acting Chief Executive is progressing work to bring these matters back to the council and I reject wholeheartedly any suggestion that she is acting improperly," Foster said.
"My own position on Shelly Bay is well known and I haven't changed that. I will keep encouraging the parties to sit down and talk about the future of this iconic site."
Meanwhile, Mau Whenua - a group of iwi members who opposed the original sale of the iwi land which is part of the development - is taking the land sale to the High Court.
