Prime Minister Jacinda Ardern says supermarkets will be closed as usual on Good Friday but will be open on Easter Sunday.

Ardern made the announcement during her daily update on the coronavirus pandemic and New Zealand's lockdown.

The Covid-19 committee's decision on Easter Trading was based on the need for staff to rest and for supermarkets to restock, but also that people needed access to essential food.

They also wanted to ensure people didn't panic buy.

Any employee who objected to working on Easter Sunday wouldn't have to work.

Ardern urged everyone to be kind to the supermarket workers.

Covid-19 test criteria widened

More than 21,000 tests have been conducted and NZ has the capacity to test about 3,500 people a day.

Ardern admitted authorities weren't testing widely enough to tell where the community outbreaks were so the case definition has been expanded.

Travel history and connection with a case was now not essential to being tested.

"I want more tests. We've built the capacity for more tests."

She said clinicians were deciding when it was appropriate to extend test criteria, not politicians.

Asked whether it was acceptable the testing criteria was only being expanded a week after the WHO urged: "test, test, test", she said NZ's testing numbers were really high and believed that message wasn't aimed at this country.

She thanked the more than 1000 pharmacies across New Zealand for their work and support.

Asked whether it was time to get tougher on Kiwis coming back into NZ, Ardern said checks had shown "by and large" there was compliance.

Asked whether there was a level of trust involved, she said those who were found not to be complying with self-isolation would be fined or quarantined.

She said the concern was were infection couldn't be traced, it was not necessarily about clusters.

Community newspapers to still be published

Ardern said Kiwis needed to have on-going access to different media voices so the Government has reversed the decision that community and non-daily newspapers are non-essential during the lockdown.

However, delivery would have to be through already existing channels.

Ardern said the Government would continue to work with media companies to "cushion the blow" of the impacts of Covid-19.

Ardern said they recognised the essential role media played during the lockdown and urged media companies to access the wage subsidy.

Ardern said they hadn't made any decisions about expanding the wage subsidy beyond 12 weeks.

Kiwis in Australia

Speaking about Kiwis in Australia now being able to access welfare, she said she was pleased they were being acknowledged for their contribution to the economy across the Tasman.

Ardern spoke with Australian PM Scott Morrison yesterday morning.

Ideally, she would like to see access to welfare continue beyond the Covid-19 pandemic.

Ardern said extending the national state of emergency was vital to the country's response to the virus.

The announcement that PPE would be dispersed more widely would be good news for many, she said.