Dr Ashley Bloomfield says there are 20 new cases - 6 confirmed and 14 probable.

The Prime Minister and Dr. Ashley Bloomfield will both take a 20 per cent pay cut, along with all ministers and public sector CEOs.

Jacinda Ardern announced the pay cut at her daily Covid-19 press conference.

The cut will last for six months, and also includes public service chief executives.

For Ardern the cut will be worth roughly $47,000, while for Bloomfield it will be worth roughly $52,000.

KEVIN STENT/SUPPLIED Jacinda Ardern has annouced ministers will take a 20 per cent pay cut.

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Prime Ministers in New Zealand earn a high salary compared to other leaders around the world, but generally less than top public sector CEOs such as Bloomfield.

It will save roughly $2.4 million, with the bulk of that coming from public sector CEO salaries, with approximately $1.6 million saved.

Savings from ministers, both inside and outside of cabinet, the deputy prime minister and the prime minister, would come to approximately $792,500.

Ardern said the cut would not change the government's fiscal position, but was instead about showing leadership.

The cut will not extend to staff on the front line of the fight against Covid-19.

"Many people in our public sector are our front line essential workers, nurses, police, health care professionals, we are not suggesting pay cuts here, nor would New Zealanders find that appropriate."

"We feel acutely the struggle that many New Zealanders are facing, and so to do the people I work with on a daily basis.

"It stands alongside many actions taken by many people, private sector, citizens, to tackle the health and economic challenges of Covid-19.

"If there was ever a time to close the gap between groups of people across New Zealand in different positions it is now."

National Party Leader Simon Bridges announced on Twitter that he would also be taking a 20 per cent pay cut.

ACT leader David Seymour has been pushing for some kind of pay cut for ministers for some time.

On Wednesday he said it was "the right thing to do" but hoped Parliament would pass a bill to cut the pay of all MPs, not just members of the executive.

Green Party co-leader James Shaw said the party supported the changes.

"We thought it was important that Green Ministers demonstrated that we are in this together, and there was unanimous support for us to opt-in to this reduction."

State Services Commissioner Peter Hughes also supported the changes, saying that with people across the country struggling financially, it was appropriate the public sector also tightened its belt.

State Services Minister Chris Hipkins said the decision was made in principal, and the government would now work through the mechanisms to make it happen.