Margrain said the park would reopen when it was ready.
"We're over halfway through our building programme but there's still a lot of work to be done. The target for reopening is the end of the year and we'll keep working towards it."
Margrain said the spend of well over $1m demonstrated the park's commitment to do the job well and that took time.
The park's forcus was on animal welfare and staff safety, he said. The trustees would work constructively with MPI and other agencies during the remedial work process.
MPI first ordered the park closed to the public between July 1 and July 31, 2014, while the animal enclosures were upgraded to meet new standards.
The closure was extended until August 31 the same year. But three years later the upgrade has still not been finished.
Margrain said the animals were in good health and all have remained on site during the work.
The park has 27 animals— 19 lions, five tigers, two cheetahs and a leopard.
If it is granted the necessary approvals under the Biosecurity Act and can open to the public, there is neither a timeframe by which it must open, nor a necessity to do so. It will be at the discretion of the park owners.