COVID-19: Aucklanders can reunite with their families for Christmas - but how will the border work? Jacinda Ardern still unsure

Aucklanders will be able to reunite with their families for the Christmas holidays, Prime Minister Jacinda Ardern has once again reiterated.

But how the border could be managed to allow Aucklanders in and out of the city remains a mystery, as does a date for when people could resume interregional travel.

Ardern says about 40,000 people will want to cross the Auckland border each day when it eventually opens for the holidays, a surge that will present "logistical challenges".

"We haven't given a date," she told The AM Show. "We've never had a hard land boundary in New Zealand for an event like this and what we've had in place was only ever designed to be temporary so the issue we'll have is; over summer, 30,000 to 40,000 vehicles a day seeking to move and, at that point, checking things like testing and vaccine certificates for every occupant in a car - you can imagine what logistical challenges that presents.

"We've been working through the range of options in order to make sure we meet that objective that we have set ourselves."

One of the controversial options raised last week was allocating time slots for Aucklanders to leave the region, a suggestion described as "raving mad" and a "dystopian future plan" by the Opposition.

Ardern said no final decisions or dates have been set.

"I understand that people want to know, I absolutely do… We've given the commitment, we know we need to enable people to move but this is a once-in-a-generation pandemic situation where we're trying to establish something that, historically, New Zealand has never had.

"The closest thing we have are toll booths and it's vastly different from what we're trying to operate. At the same time, it was only ever designed to be a temporary solution."