Prime Minister Jacinda Ardern says the travel ban on foreign nationals coming to New Zealand from mainland China is likely be extended.

But she said there have been no discussions about including other countries, despite new positives tests in places such as Italy, which now has 152 confirmed cases.

"No one here is proposing that we put in place a travel ban that basically starts picking up Europe and the like," Ardern told Newstalk ZB's Mike Hosking this morning.

An initial two-week ban was put in place in early February to try keep the coronavirus out of the country, and it was then extended for a further eight days.

The ban is being reviewed every 48 hours and was going to expire today, but Cabinet will meet today and discuss extending it.

"Based on the evidence we have, I am anticipating that the result of Cabinet's discussion will be an extension," Ardern said.

The Chinese Ambassador to New Zealand Wu Xi has questioned why the ban was imposed against the advice of the World Health Organisation.

New Zealand citizens, permanent residents and their immediate family are excluded from the ban, but are being told to self-isolate for 14 days after arrival.

The Australian government has extended its ban to Saturday, but is allowing some high school pupils from China to enter on a case-by-case basis.

Universities NZ has asked the Government for an exemption for foreign students stuck in China, and Ardern said the Government was still considering this.

But she appeared to hint that an exemption would be unlikely.

"There's no point doing this unless we can guarantee people would be quarantined properly."

Asked if an exemption would be too difficult, she said: "I don't want to say that yet. We are really properly teasing it out. We owe it to the sector to do that."

Meanwhile Ardern defended the delays in forming the Government's vaping policy, which was announced yesterday.

Ardern said the Government had taken its time because it had waited for evidence on vaping to emerge.

She said if she had been asked at the beginning, she would have banned vaping flavours altogether, but the Government's new bill would allow them to be sold in speciality R18 stores.

"The small body of evidence we've had emerging has shown that, actually, that has been important to people as a cessation tool to stop smoking," Ardern said.

"We've based it on the evidence we've had once we've had it - and there hasn't been a lot."

Ardern also said that the Government's feebate scheme to incentivise people to buy more fuel-efficient vehicles wasn't dead in the water.

The National Party tweeted at the weekend that it had killed the policy, only for New Zealand First to super-impose its own logo on the National ad to claim it had actually killed it.

"We haven't concluded conversations," Ardern said.

"Most countries have standards or restrictions or incentives around fuel efficient cars. I don't think New Zealand should be unique in the fact that we don't.

"We want lower emission vehicles. These are all options to try and achieve that."

Asked if the feebate policy was never going to see the light of day, she said: "I would not say that."