Green Party co-leader James Shaw says the National Party's leadership are spreading "incredibly dangerous" misinformation.
Shaw said now was not the time for conspiracies, but for leaders from all stripes to support a strong public health message directed by science.
"I have been disheartened to see some leaders cast doubt on the developments and associated decision making over the last 48 hours.
"To create confusion and suspicion quite frankly could result in reduced trust from our communities in the very institutions we rely on most to keep us all safe.
"This could lead to less willingness to pitch in to stamp out the virus. This puts us all at risk."
Shaw is currently awaiting the result of a precautionary Covid-19 test after travelling to South Auckland at the weekend then developing minor cold symptoms after returning to Wellington.
National deputy leader Gerry Brownlee came under fire yesterday for questioning when Prime Minister Jacinda Ardern knew about the new confirmed Covid-19 cases.
Brownlee listed an allegedly suspicious series of events, including director general of health Ashley Bloomfield telling New Zealanders to prepare for a second wave and to have masks prepared.
"Then you saw the Prime Minister's visit to the mask factory ... along with Dr Bloomfield, after 103 days of no community transmission having a test himself - all very interesting things to happen a matter of hours before there was a notification of the largest residential part of New Zealand going into level 3 lockdown," Brownlee said.
Brownlee was questioned by journalists about what he was implying and replied: "I'm just outlining facts ... it's an interesting series of facts."
He has previously called on the Government to "come clean" about what it knew about the state of Covid-19 in New Zealand.
National leader Judith Collins has also accused the Government of failing to be transparent.
"I have been given very scant information," Collins said.
Shaw today said the National leaders' rhetoric was "incredibly dangerous" and he was worried Brownlee was spreading misinformation at a time there was a susceptibility to conspiracy theories.
He said there was a "real risk" it would undermine the public's buy-in, especially when there could be a weariness by New Zealanders to go through another lockdown.
"You may find that people are less willing to do what it takes to stamp out the virus this time than they were last time.
"And the risk is that when you see the kind of behaviour you've seen by Judith Collins and Gerry Brownlee over the last 24 hours, [that fatigue] will be exacerbated."
Shaw said there were completely legitimate ways for the Opposition to critique the Government's response which was the public health response - not "whether there's a conspiracy at the level of Cabinet to cover up information".
The Greens' position on the election
Shaw said they would only support moving the election if the Electoral Commission gave advice it wasn't viable to hold a credible election on September 19.
And he accused those calling for a date change to be doing so "out of political self-interest".
Collins yesterday called for Ardern to delay the election until at least after November and went as far as to say National's preference was for it to be held next year to give parties time to campaign.
NZ First leader Winston Peters said the health of New Zealanders should come before politics and if that meant the upcoming election had to be delayed, "so be it".
And Act leader David Seymour said yesterday if the alert levels were extended beyond Friday midnight, the election should be delayed to ensure it was "free and fair".
All major political parties have cancelled their campaigns because of the new community transmission outbreak in Auckland.
Shaw said the problem with delaying the election was there was no way to introduce any certainty "in a pandemic of epic proportions".
Not being able to campaign would be a challenge for the Greens - which were on 5.4 per cent in yesterday's UMR poll putting them right on the 5 per cent threshold to get back into Parliament.
But there were ways it could be done online and in small socially-distanced public meetings if regions stayed in alert level 2, Shaw said.
"I accept it's incredibly challenging not just for the Opposition, but for the Greens as well. But we just have to deal with it."