Prime Minister Jacinda Ardern has announced Covid-19 restrictions will continue at their current level until at least 11.59pm on Sunday night.

Masks will also be mandatory from Monday when using public transport at level 2 and above.

Announcing Cabinet's decision at 3pm after a meeting today, Ardern says the rest of the country will remain at level 2.

The current restrictions - Auckland at alert level 3, and the rest of the country at level 2 - had been due to lift at midnight Wednesday and ministers met this afternoon to review whether community transmission has been contained.

Director-General of Health Dr Ashley Bloomfield briefed Cabinet on cases, trends, progress finding the index case, the spread of the virus and whether there are any cases still not linked to the Auckland cluster.

Aucklanders have been divided on the matter, but the city's mayor and businesses supported an ease of restrictions.

Ardern says keeping New Zealand at level 2 is important because of regional travel - many people will want to enter and leave Auckland once it moves into level 2.

This comes with risk, she says, with Cabinet "constantly keeping in mind the cost to business, the cost to the Auckland economy".

"It's a finely balanced decision, but the right one, I believe."

The wage subsidy two-week extension will be kept as is.

She says they considered moving the rest of the country to level 1 but it would be hard to police Aucklanders going across the country to attend mass gatherings.

Exponential growth in the cluster or cases that aren't able to be linked to the cluster would mean things would change, she says.

She says the government is sticking with its "stamp it out" strategy, and acknowledges many would have found it harder this time.

"We may not have any choice about whether or not the world is in a global pandemic but we do have choices about how we deal with it."

The limits on mass gatherings to 10 and tangihanga and funerals to 50 are only for Auckland, she says. The rest of the country will have the usual level 2 gathering limits.

The wage subsidy two-week extension will be kept as is. Adding days to the wage subsidy is not a simple exercise, Ardern says, and keeping it as is allows the money to keep flowing out to people fast.

Ardern says people need to check the list of exemptions for travel through Auckland before applying for one, so they do not clog the process for others. She says some people whose reasons for exemption are already on the list are requesting them when they do not need to.

Masks to be mandatory on public transport

Ardern has also announced Cabinet's decision to make masks mandatory on public transport. She says it will apply at level 2 and above, and will come into effect from Monday.

Children will not be required to wear masks, but an exact age is being worked on. Taxis and rideshare services like Uber are included in the rule.

"We continue to ask everyone on public transport or planes to wear a mask," she says. "They limit the chance for Covid-19, when it is often harder to distance yourself and trace people."

She's not worried about the availability of masks but encourages people to explore buying alternatives to single-use masks if they can afford to, or to fashion a mask from things found at home.

She says it's a face covering, and the type of mask used is not being policed. Advice on different types of face coverings will be available online.

"This is a commonsense approach to protect everyone's health."

She doesn't want to see the public people policing other's use of masks but if someone were to offer another person a mask then that would be a kind thing to do, she says.

She says they continue to encourage the use of masks between now and Monday

Cabinet was very, very clear on mask use and it was not concerned about people's response to this as New Zealanders are very pragmatic, Ardern says.

Two weeks since new community cases

Beginning her post-Cabinet briefing, Ardern says tomorrow marks 14 days since the reemergence of Covid-19 outside of quarantine facilities.

Cases have emerged over the past 13 days of cases that occured before Auckland went into level 3, she says, and if it were not for level three, the cluster would be much larger.

She says more than a quarter of the testing done across the country has been done in the past 13 days.

The next several weeks will see more cases, she says, but also thousands of tests and a team in full force to stamp out Covid in New Zealand.

New Zealand knows how to bounce back, she says.

"We are strong, we have been kind and we are doing really well."

Ardern says the whole world has been learning and New Zealand has been improving and learning throughout the pandemic.

From Friday's data, testing among the Pasifika community was high, she says. Pasifika represent about 20 percent of the testing, well over the percentage of Pasifika represents in the community.

"Without those members of our community being willing to be testing, lives would have been lost - particularly to our Pasifika community ... I want to say thank you."

The Prime Minister Jacinda Ardern says while the Auckland cluster is contained it is our biggest one.

She says that means the tail will be long, and the cases will keep coming for a while to come.

Today there were eight new cases of Covid-19 in the community, plus a case which arrived from overseas into managed isolation.