New Zealand could stay closed to safer Australian states for months, tying their trans-Tasman bubble fates to COVID-19 crisis state NSW.
Jacinda Ardern's government has signalled a shift away from state-based openings with Australia when - and if - it re-opens the trans-Tasman bubble later this year.
On Friday, Ms Ardern canned quarantine-free travel from Australia for an eight-week stretch, due to last until September 18.
New Zealand's health authorities recommended a bubble break on the back of the "game-changing" Delta variant present in NSW.
Since the bubble opened in April, New Zealand has shifted states and territories in and out of the border arrangement according to local cases.
But Deputy Prime Minister Grant Robertson told TVNZ his government was now looking at a one-in, all-in approach that could see safer states like Western Australia and Tasmania treated the same way as those with outbreaks.
"The precautionary approach says you need to look at this Australia-wide," he said.
"The reality, particularly on the mainland of Australia, is that unfortunately those are big borders ... once (Delta) gets in there it is difficult to contain.
"We still think we can operate a trans-Tasman travel bubble but we think we need to have Delta under control."
Ms Ardern said she was worried about the ability of Australian states to prevent cases crossing borders, citing it as a reason for the eight-week break.
"It was about not only the outbreak in NSW but the ability to contain an outbreak despite a state border ... we are seeing leakage," she told TVNZ.
"This was about shutting down the risk entirely."
Mr Robertson said a re-opening was not dependent on NSW eliminating COVID-19 completely.
"It doesn't mean zero cases per se but it means we can reliably predict where the cases will be," he said, referencing cases found among people already isolating.
The bubble closure has sparked a rush on Kiwis returning home.
The NZ government has given Kiwis until Friday to get back to Aotearoa before it enforces quarantine requirements on all incoming travellers.
Some 21,000 New Zealanders have travelled to Australia without returning since borders were opened, but the government doesn't known how many want to fly back.
Ms Ardern said she was open to extending Friday's quarantine-free deadline if demand exceeds current flight capacity.
"Our only way of knowing whether or not we're going to meet demand is by seeing whether or not there's capacity left on flights," she said.
With limited space in NZ's quarantine facilities available, Ms Ardern's message to Kiwis in Australia was direct.
"I implore anyone who's currently in Australia ... if there's a likelihood you need to be back in New Zealand, I would encourage you to come back," she said.
Australian Associated Press
