Coronavirus: Foreign travellers who fail to self-isolate could be deported - Prime Minister Jacinda Ardern

Prime Minister Jacinda Ardern says foreign travellers who fail to self-isolate after arriving in New Zealand may be deported.

Her comments come after strict travel restrictions came into effect overnight, forcing everyone arriving from overseas - with the exception of those arriving from the Pacific Islands - to self-isolate for 14 days in a bid to stop the spread of coronavirus.

Cruise ships will also be banned from entering the country until at least June 30.

Newshub reporter Juliet Speedy visited Christchurch airport on Monday morning to speak with passengers arriving in the country.

Although most Kiwis arriving home said they accepted the self-isolation rules as a necessary inconvenience, a number of European backpackers told her that though they will try to keep their distance from people, they would not be delaying their plans to travel around the country in a campervan.

Ardern said it's possible that tourists who ignore the self-isolation rules could be forcibly quarantined or even deported.

"While we're at a period where actually we might still have some international travellers coming in, [it's important] that they know exactly what the expectations are of them and what our powers are if they do not follow them," Ardern told The AM Show on Monday.

"We have the ability to quarantine them - put them in a facility, quarantine them, have a police officer stand outside the door and make sure they don't leave. But I've also asked the question whether I have the power to deport as well," she said.

"I expect that the answer if it's not [yes] then I will then ask for the power to deport - I don't think it will come to that."

Professor Michael Baker, an expert in infectious diseases at Otago University's department of public health, told Magic Talk it would be irresponsible for travellers not to follow the order to self-isolate. However, it was possible to follow the advice while still travelling.

"If people are blatantly disregarding it that's really irresponsible. But what I would say is if you've got a family group that has arrived from, say Melbourne, they're in their campervan as a family unit, they're travelling around, that is a form of self-isolation if they're not having contact with other people.

"The essence is contact with people - it doesn't mean you have to sit in one spot."

Ardern said she was aware that the stringent measures would hit the already struggling tourism industry.

"Essentially it means people stop coming - that is the impact, that's why obviously we've already said we know this will have implications for airlines and we know that we will have to do some work there and that's something we fully expect."

When announcing the measures over the weekend, Ardern said they were "about restricting the movement of people, not products".

Cargo ships and essential flights carrying items such as pharmaceuticals will not be affected, she said.

"We will continue to have imports come into New Zealand."

The restrictions would be reviewed in 16 days, but people should "be prepared" for an extension, Ardern told The AM Show.

"Everybody should prepare, that would be wise under the current circumstances. But I also feel I do need to keep reminding people, border restrictions are only one of the measures that we need to take.  We would be wrong to assume that that is the only measure and that we need do nothing else. 

"New Zealand will have more cases, we will have more cases."

On Monday the Reserve Bank announced it would cut the official cash rate (OCR) to a record-low 0.25 percent to combat the economic fallout caused by the pandemic.

The rate would remain at that point for a minimum of one year, the bank's governor Adrian Orr said.

Ardern said the Reserve Bank's decision would help give a little certainty to businesses.

"Whilst obviously these decisions are absolutely for the Reserve Bank, we have as a Government via the Treasury been coordinating activity and I think business will be looking to make sure that everything that we're all doing is focused on making sure that we're as resilient, as prepared and supportive of business right now as we can be," Ardern said.

The Government will be announcing a business contingency package on Tuesday, which Ardern said would be "sizable" and "multi-billion-dollar".

So far eight cases of COVID-19 have been confirmed in the country.