The Government has confirmed it is restricting seats on international flights for people wanting to return to New Zealand.

In a statement this morning Minister Megan Woods said the Government and Air New Zealand had agreed to manage incoming bookings in the short term.

This would enable the Government to safely place New Zealanders arriving home into a managed isolation or quarantine facility, said Woods.

Woods, speaking to media at 10am, said "we were never going to let" border facilities reach maximum capacity.

But it became apparent they needed to take action, she said.

Woods said New Zealand wasn't running out of space, but it needed to be managed.

"We cannot let this continue to be a purely demand-driven system".

She reiterated Kiwis booked on flights over the next three weeks would still be able to come back and these measures would be short term. She expected the block on new bookings would last for three weeks.

That would help the Government have more certainty about exactly how many people were coming in.

"People that have a ticket will still be able to complete their journeys."

Woods said it was about bringing New Zealanders home "in a safe way".

"We're doing this so we can ensure we have that very strong line of defence."

Since June 17, almost a third (28 per cent) of all the 27,000 who've been through the facilities which Woods said showed the demand.

She assured New Zealanders they still would be able to come home.

Air New Zealand makes up about 80 per cent of the inflow into the country so it was critical they were on board. They were in talks with other airlines to take similar measures, Woods said.

Airlines realised they needed to be responsible and were part of the defence of Covid-19, Woods said.

The last repatriation flight from India happened on July 3.

"This is a large and complex operation and anyone saying it's simple should take a look at one of the complex systems I've ever seen."

Woods said setting up a border facility wasn't as simple as booking a hotel and they were looking to build more facilities but it was complex.

"It is complex and it is complicated but it is critical that we get it right."

One of the criteria from the Health Ministry is that a facility has a separated bathroom space. Many of the "more institutional" facilities didn't meet that, she said.

The Government was continually getting legal advice on human rights about the facilities and that the three-week delay didn't impact on Kiwis' rights to come home.

Woods hasn't had discussions with Air New Zealand about the potential financial impact of the measures.

The Government was still looking at compassionate leave from isolation, including transport and compliance.

Someone with a booking a month out can still come back but there won't be any new bookings for three weeks.

There had been more people coming in on flights than expected during the past couple of weeks, she said.

Previously there were a lot of no-shows on flights, but as life was somewhat returning to normal overseas, more people were making their bookings.

"We have to bear in mind that around the world Covid is growing, not slowing."

The Government was working through details of exceptions to the rule for emergencies with Air New Zealand and Woods said airlines dealt with that sort of thing a lot.

Woods' message to Kiwis now having to wait was "thank you" and the decision - in order to make sure the country's gains weren't jeopardised - was there needed to be secure border facilities.

Those facilities were one of the key reasons there was no community transmission in New Zealand, she said.

In a statement earlier today, she said she and Air Commodore Darryn Webb "met with Air New Zealand's chief executive Greg Foran to discuss safe and robust ways to jointly manage the big growth in New Zealanders coming home," Woods said.

"Air New Zealand has agreed to put a temporary hold on new bookings in the short term, as well as looking at aligning daily arrivals with the capacity available at managed isolation facilities.

"People who have already booked flights with Air New Zealand will still be able to enter New Zealand subject to availability of quarantine space.

"We are seeing rapid growth in the numbers of New Zealander coming home as the Covid-19 pandemic worsens.

"Our number one priority is stopping the virus at the border, so everyone must go into quarantine or managed isolation. The Government is also talking to other airlines about managing flows.

"The last thing we need are hastily set up facilities to meet demand, so we must have a manageable number of fit-for-purpose, safe facilities that do the job of stopping Covid at the border."

Webb said there were now nearly 6000 people in 28 managed isolation facilities.

"[We] are scaling up more spaces all the time, but we need to do so safely and new facilities need to be watertight before they are opened.

"These temporary measures will ease the current demand on facilities while additional supply is brought on line. In the past three weeks we have brought on capacity 10 new facilities for 2000 more people, and have a plan to bring on another 750 places in the coming weeks.

"The pause on new bookings will be short-term, and allows us to increase supply to match forecasted demand over the coming weeks."

The Government was also talking to other airlines about managing flows, Woods revealed.

Woods said there had been similar moves in Australia, where passenger numbers into Sydney had been limited following the suspension of flights into Melbourne because of the surge in Covid-19 cases in Victoria. They were also having to manage the flow of people into the country to match availability of managed isolation beds.

The numbers of those arriving had continued to increase in recent weeks, with 5697 people currently in managed isolation and quarantine.

Air NZ responds

Air New Zealand this morning confirmed it had put a hold on new bookings for international services landing in New Zealand following a request from the Government.

As well as the temporary hold on new bookings for the next three weeks, the airline was also looking at aligning daily arrivals with the capacity available at managed isolation facilities. This might mean some passengers would need to be moved to another flight and have travel plans disrupted.

The airline said the move was to help ensure the country was able to provide quarantine accommodation for inbound passengers for the required 14-day period.

Air New Zealand chief commercial and customer officer Cam Wallace said the airline had been working closely with the Government to understand how it could support efforts to contain Covid-19 at the border.

"We accept this is a necessary short-term measure given the limited capacity in quarantine facilities and we're keen to do what we can to help New Zealand's continued success in its fight against Covid-19."

The airline was contacting customers affected by these changes from today.

The airline's contact centre was currently experiencing very high demand, and customers were asked to contact the airline through social media channels. Those who booked using a travel agent, including third-party websites such as Expedia and Booking.com, were advised to speak directly with their agent.

Those leaving the country on Air New Zealand flights were not affected by the latest restrictions. Domestic flights were not impacted.