A state of emergency was declared in New Zealand by the Minister for Civil Defence Peeni Henare on Wednesday afternoon as the number of infections soared to 205 overnight - a rise of nearly 50 per cent.
New Zealand is attempting to eliminate the virus before it takes hold, having seen the devastation caused in countries such as Italy, where the authorities acted too late.
Prime Minister Jacinda Ardern has said Kiwis returning home will be placed in quarantine.
"You can not physically quarantine every person coming back to New Zealand at the moment, so you focus on those who are high risk, and those with symptoms in particular".
She told residents that the number of people infected would rise, possibly by thousands.
Civil Defence Minister Peeni Henare speaks during question time at Parliament on December 11, 2019 in Wellington, New Zealand.
Infectious disease specialist Dr Richard Everts prepares to test patients a Covid-19 community based assessment centre in Tahunanui, Nelson.
Stuart-Black said these powers sat alongside other powers to ensure essential services could stay up and running. "The Police will monitor them and anyone found violating the order will be fined and quarantined", she said.
Stuart-Black would be empowered by the state of emergency powers, but she said it would be great if she didn't have to use them.
Kiwis will be notified of the lockdown by a text message between 6pm and 7pm tonight.
The legislation allowed the state of emergency to remain in place for seven days, but this can be extended.
New Zealand borders will be open for returning New Zealanders but all of them will be screened at their port of arrival, Prime Minister Jacinda Ardern has said.
Despite the rising number of cases, most who contract the virus suffer only mild symptoms before making a recovery.
It is understood that about 10,000 New Zealanders, now overseas, are expected to return home by the end of the month.
The government has commandeered the defence force to assist police to uphold public safety and enforce the lockdown, which begins at midnight on Wednesday. It also provides access to powers that would not normally be available but would be needed to support the delivery and timely response to Covid-19.
New Zealand will quarantine up to 10,000 Kiwis returning from overseas, under strict new border measures to control the spread of coronavirus.
The Reserve Bank has reduced the Official Cash Rate to 0.25%, relaxed capital requirements of retail banks and purchased government bonds valued at $30 billion to maintain currency flow, while retail banks have also stepped their levels of assistance. "We will get through this if we all continue to work together", he said.