National leader Judith Collins question's Government's transparency over community transmission

National leader Judith Collins has questioned the transparency of the Government regarding New Zealand's new cases of community transmission.

Prime Minister Jacinda Ardern announced the new cases in a press conference with Director-General of Health Dr Ashley Bloomfield on Tuesday at 9:30pm.

Dr Bloomfield had been told of the four cases around 2:40pm and the Prime Minister after an event at 4pm.

On Wednesday the Leader of the Opposition Judith Collins said she was surprised to have only been informed by Ardern during a phone call at 8:45pm.

"Only about half an hour before the scheduled press conference, she telephoned me and advised me that they believed there was community transmission and they could not find the source of where this had come," Collins said.

"It is very important at a time like, especially when we are only five weeks out from an election, and only a few weeks out from the opening of polling booths that we have the Government respecting the pre-election conventions.

"It is always a part of our pre-election conventions that the Government does not make major decisions without a full consultation with the Opposition. Just advising the leader of the Opposition, like myself, just before a public announcement is not consultation."

Collins also said it was not acceptable that National's health spokesman Dr Shane Reti had been asking for a briefing from the Minister of Health Chris Hipkins and health officials "all day" and not yet received one.

"He was promised one for 12pm today, it's now after 3 o'clock and phone calls have been made on an almost half-hour basis trying to secure that," she said.

"It is important that the Government is transparent. It has not been transparent so far and the fact that we are still waiting all day for a briefing on the health situation tells me that they are not prepared to be transparent."

Collins confirmed she had "heard a lot of rumours" the Government knew of the cases even earlier but said Ardern had assured her she only found out at 4pm.

In a press conference earlier on Wednesday Ardern also rubbished the rumours her Government had withheld information about the new cases from the public.

"I have heard suggestions we may have had this information earlier than we said we did. There is absolutely no reason why we would ever do that," she told reporters.

"We moved very quickly, including to inform the public and I do worry that those theories do nothing to support what needs to be collective action from all of us."

Director-General of Health Dr Ashley Bloomfield agreed, saying they informed the public as soon as they could.

"We needed to have a certain amount of information to inform what are already quite significant decisions about moving Auckland to alert level 3 and the country to alert level 2," he said.