Prime Minister Jacinda Ardern has announced all travellers will have to self-isolate on their arrival to New Zealand, apart from those coming from the Pacific Islands.

She said the measures - in effect as of midnight Sunday - include New Zealanders.

The restrictions will be reviewed in 16 days and there will be more advice for self-isolation next week.

It will be the strictest border restriction rules in the world, Arden said.

"I make no apologies. This is an unprecedented time.

"If you don't need to travel overseas, then don't. Enjoy your own backyard for a time. Stop handshakes, hugs and hongi."

"We are a tough, resilient people. We have been here before.

"We are taking every step we can as a Government."

All cruise ships are also being asked to not come to New Zealand until June 30. It does not apply for cargo ships.

Essential air freight will still be allowed to enter the country for things like pharmaceuticals.

The PM says our pandemic which hits hard and fast must be dealt with by "flattening the curve" to have the rate of cases in the right place- either at home on in hospital if needed.

"We must go hard and fast."

She urged people there was no need for anyone to "take a run on their supermarket".

Up until today, travel restrictions in New Zealand included preventing foreign nationals travelling from or transiting through mainland China or Iran from entering New Zealand.

People exempt from the temporary restrictions were self-isolating for 14 days after their return.

People who had been in Italy or the Republic of Korea (excluding airport transfer) were required to self-isolate for 14 days after their return.

And people who had travelled to Hong Kong, Japan, Singapore and Thailand (excluding airport transit) are being asked to aware of coronavirus symptoms but do not need to self-isolate if they are well.

Ardern said New Zealand was already registering all travelers who are self isolating once entering NZ the PM said. 10,500 people have already self isolated in NZ.

President Donald Trump announced on Thursday he was suspending all travel between the United States and Europe for 30 days.

The World Health Organisation has declared the coronavirus a pandemic as the number of confirmed cases globally reaches 145,000. Just over 5400 people have died. Almost 70,000 people have recovered.

It was announced today New Zealand now has its sixth positive case of the coronavirus, an Auckland man.

There also two probable cases of Covid-19 in New Zealand.

Aged in his 60s, the man recently returned to New Zealand from New Jersey, United States and was at home recovering in self-isolation.

Waitematā District Health Board chief executive Dr Dale Bramley confirmed the news to the media on Saturday afternoon.

Bramley was alerted to the sixth case on Friday and the man, who was doing well at home, did not require hospital treatment.

There was still no community spread of the virus, Bramley said.

Flying home from New Jersey via Houston, no one else on the flight should be alarmed because they were not regarded as being close contact, he said, because the feeling unwell until more than three days after he arrived back in the country, the Ministry of Health said in a statement.

The man did attend the 8.30am service at St Mary's church on East St, Papakura before he became unwell and as a precaution. Close contacts were being contacted and put into self-isolation.

Family contacts of the man would also be offered testing and contact tracing was under way in Auckland, the ministry said.

The sixth confirmed case would be monitored daily by health services, Bramley said.

After starting to feel ill, the man did everything right by phoning ahead to his doctor and telling them of his travel history, about a possible link and his symptoms.

He was then assessed in his car by his GP, who was wearing the appropriate protective equipment.

Protective gear, which includes a gown, goggles, face mask, and gloves had been sent to 420 GP practices across Auckland, Bramley said.

The two previous patients in hospital - one confirmed case and another probable - were now back at home recovering with daily checks undertaken by health staff.

All close contacts of the other five confirmed cases - 252 total - were in self-isolation and were also being monitored daily by health staff, the ministry said.

Community members who were sick were told by Bramley to stay at home and not head out to public events or even work.

The advice for the public remained the same, the ministry said.

Anyone feeling unwell should ring Healthline on the dedicated Covid-19 number: 0800 358 5453 or alert their GP who would advise them.