Beijing-based company Fu Wah says a shortage of skilled workers in New Zealand's construction sector risked delaying the project.
Its New Zealand general manager Richard Aitken says they planned on bringing up to 200 workers from China to help the 300 local staff already on site.
Fu Wah says the first of the workers, due to arrive next month, would mainly be involved in decorating finishes such as stonework, tiling and wallpapering.
A briefing from the Ministry of Business, Innovation and Employment to Immigration Minister Iain Lees-Galloway revealed the government only found out about the plan on Thursday - after RNZ News reported on it.
And Mr Lees-Galloway said the application for temporary work visas was made on Friday.
The briefing said Immigration New Zealand would consult Work and Income and relevant industry training organisations on the application.
"Approval in principle applications which involve this number of workers are signed off at assistant general manager level," the briefing said.
Mr Lees-Galloway says he did not know how long the application would take to be processed.
"My understanding is that an application for approval in principle was received by Immigration on Friday morning.
"Work has to be done to assess that application, until that assessment is done no visas can be issued.
"At this stage it is simply an application and nothing has been decided. So those workers will not be able to arrive until a decision has been made."
Mr Lees-Galloway says it would be prejudicial to make any comment on the merit of the application.
"We have seen in the media that the company has some expectations on when the workers will arrive - but the process will take as long as necessary.
"I'm satisfied that the company has lodged its application in the normal matter. I have no concerns about it and I'm not alarmed by the large numbers it says it needs."
"I've asked officials to let me know in future about such applications so we can keep an eye on things."
He says given the shortage of skilled workers in the construction sector there would probably be more applications of the same nature in the future.