Any talk of opening up New Zealand's borders in many months to come is "dangerous," Prime Minister Jacinda Ardern says.

Responding to the National Party leader Todd Muller's suggestion earlier today that it was "untenable" to leave New Zealand cut off from international travel indefinitely, Ardern said it was "untenable to consider the idea of opening up NZ’s borders to covid-19."

"In some parts of the world where we have had frequent movement of people, they’re not estimating that they will reach a peak for at least a month or sometimes several months so we will continue on all estimates to see covid surge," she said in her weekly post-Cabinet press conference. She emphasised that total reported cases of covid-19 had topped 10 million and were continuing to rise.

"Any suggestion of borders opening at this point frankly is dangerous and I don’t think we should put NZ in that position," she said.

Muller called on the government to articulate a strategy for unlocking the country. 

“What appears to be the case is that we will stay closed until other countries have reduced their covid presence to essentially the equivalent of ours, and then we can consider opening up our border to the rest of the world. That is an untenable strategy for this country," Muller said.

“The idea that we can sit here at the bottom of the world with 20 percent of our exports off the table in terms of international students and tourism, and essentially just trade amongst ourselves for the foreseeable future, locked up to the rest of the world and waiting for a vaccine, I think is untenable," he said.

Quarantine charging

Ardern also made clear that the government would consider charging New Zealanders who chose to leave the country for non-essential reasons for the cost of quarantine on return.

The right of NZ citizens to return to the country complicated the legal right to charge for quarantine, but she hoped for an answer "sooner rather than later on charging those who are already in NZ and are deciding that they will take a trip overseas in the expectation that they will get free quarantine when they return."

That was very different from having to make an unavoidable international trip.

"I do think we should explore payment for them."

She was sympathetic to the plight of NZ tourism operators who may have hoped they would start seeing Australian tourists arrive under a trans-Tasman 'bubble' arrangement that is now on hold indefinitely as covid cases in parts of Australia climb fast.

She was open to the possibility of being able to travel to covid-free Australian states, but a decision on opening up the whole country or on a state-by-state basis was for Australia, she said.

"Obviously, where there is community outbreak that is a no-go for New Zealanders. Where they have border control and no community transmission for some time, then that may be a different scenario."

Opening up to Australian tourists too quickly could create risks for NZ tourism operators, since 60 percent-plus of all their customers were NZers and there were significant numbers of people taking local holidays at present.

Ardern also raised doubts about whether NZ was coming under pressure from Pacific Island governments to reopen air connections to allow their beleaguered tourism sectors to start operating again.

"They want to move cautiously on  behalf of their populations," she said of recent conversations with Pacific leaders.