Prime Minister Jacinda Ardern says she was only informed about the new Covid community cases about 90 minutes before the public was told.

The Government's key Covid-19 response ministers were peppered with questions from the Opposition in a socially distanced and level 2 appropriate Parliament this afternoon.

Both Act and National challenged Ardern and Covid-19 Response Minister Chris Hipkins on a number of Covid issues.

Speaking in reply to National leader Judith Collins, Ardern said she stood by her Government's actions relating to the latest Covid-19 community outbreak.

She pointed out that New Zealanders have enjoyed more freedoms than anywhere else in the world.

And to keep this being the case, she said officials are looking to tighten up processes as much as possible.

When pressed on the community case timeframe, Ardern she first learned about the new community cases between 11am and midday on Sunday.

That information was revealed to the public at 1.30pm.

"We gave ourselves quite a short timeframe," she said.

A decision to change alert level decisions was announced at 7pm that night.

But she said there were a few hours in between when neither she, nor her officials, had a clear idea as to what the best approach was.

On the issue of saliva testing, Ardern said that was not as accurate as the normal testing swabs.

But at the moment, they are done alongside the normal testing regime.

It is, however, voluntary.

Ardern clashed with National's Chris Bishop, who was heckling her as she spoke.

"I'm glad we have an expert here," she sarcastically shot back at Bishop.

Keeping with Covid-19, National's Shane Reti also pressed the Government on saliva testing.

Hipkins said that the Government had not made it compulsory, "yet".

But he said this type of testing was being progressively rolled out at MIQ facilities.

"We will use saliva testing as a complement to [regular Covid testing]."

This is because it is not yet accredited when it comes to diagnosing Covid-19, Hipkins said.

But he was at pains to point out that the Government was not ruling it out.

Later in question time, Hipkins said the LSG Sky Chef worker - one of the initial three community cases - was not wearing Covid-19-prevention standard PPE as it was not regarded as a "high-risk area".

But that is something that the Government is looking into now.

Collins' question was asking Ardern if she stands behind all her "statements and actions" related to Covid-19.

Yesterday, Speaker Trevor Mallard re-implemented the alert level 2 rules for MPs in the House.

"Physical distancing in the Chamber will be required and so the number of members in the House will be reduced," Mallard said.

He also said that numbers for each party would be allocated in proportion to their caucus size.

To make up for this, Mallard said there would be an unlimited number of proxies

available so members will not be required to travel to Wellington.

A proxy question is one asked on behalf of an MP who cannot make it to the debating chamber.