The Opposition says newly-released documents show "clear contradictions" in the government's response to Covid-19.
In a 20 March document, top health officials recommended New Zealand move to Alert Level 2, and remain there for up to 30 days.
But just three days later, the Government moved to Level 3, and in another two days went to Level 4.
National Party health spokesperson Michael Woodhouse said the Government lacked confidence.
"There are clear contradictions between what the Government saw about their response and what they were telling the New Zealand public," he said.
"They need to explain why because the costs of that lockdown, both from an economic perspective and also from the number of people with health issues that aren't related to [Covid-19] is growing by the day."
The Government proactively dumped hundreds of documents late on Friday, and in an email obtained by RNZ, the Prime Minister's office gagged her ministers by telling them not to do interviews.
"It shows a cynical disregard for the process and it makes a mockery of their claim to be open and transparent," Woodhouse said.
"The idea that ministers wouldn't front for a massive amount of information being released is just incredible to me."
The release of more than 300 documents includes papers, minutes and advice to most sectors of the Government from January until 17 April.
One of the earliest papers dates back to January 28, when a Cabinet minute discussed a low risk to New Zealand but a potentially serious risk to public health.
Other official documents discuss the decision-making centred on alert levels and restrictions, the border, public health, housing, income support and foreign affairs.