New Zealand Prime Minister Jacinda Ardern on Wednesday declared a state of national emergency as the country prepared to go into a complete lockdown at midnight to combat the coronavirus outbreak.

New Zealand's cases of the coronavirus surged to 205 cases as the government imposed self-isolation for everyone, with all non-essential services, schools and offices to be shut for a month.

"From midnight tonight, we bunker down for four weeks to try and stop the virus in its tracks, to break the chain," Ardern told parliament.