New Zealanders have tonight received an alert to their phones from Civil Defence as the country prepares to go into lockdown.

It read:

This message is for all of New Zealand.

We are depending on you. Follow the rules and STAY HOME. Act as if you have Covid-19. This will save lives.

Remember:

• Where you stay tonight is where YOU MUST stay from now on
• You must only be in physical contact with those you are living with

It is likely level 4 measures will stay in place for a number of weeks.

Let's all do our bit to unite against Covid-19.

Kia Kaha.

State of emergency explained

It was declared at 12.21pm, and applies to all of New Zealand - including the Chatham Islands, Stewart Island and other inhabited islands.

Civil Defence earlier said a nationwide mobile alert would be issued to all New Zealanders between 6-7pm.

The State of Emergency legislation allows it to be in place for seven days and can be extended.

The Minister for Civil Defence Peeni Henare announced the State of National Emergency.

The National Emergency Management Agency (NEMA) supports Civil Defence Emergency Management (CDEM) Groups in their planning and operations.

NEMA is in charge in a State of National Emergency. CDEM says these types of emergencies are rare. The only one like this was the Christchurch Earthquake of February 2011.

Earlier this week, Civil Defence Emergency Management (CDEM) director Sarah Stuart-Black said powers under a national state of emergency would "enable us to be able to close or restrict access to roads or public places, remove or secure dangerous structures or materials, provide rescue, first aid, food, shelter, conserve essential supplies, regulate traffic, dispose of fatalities in terms of people that have passed away or animals, enter into premises to rescue people or save lives, evacuate premises or places, remove vehicles and vessels, requisition equipment and materials and assistance".

She said tasks required by CDEM would be carried out be central and local government, emergency services, the defence force and a range of other agencies.

Today, Stuart-Black said the State of National Emergency provided access to powers that were not normally available, but were necessary.

She said the powers were complementary to the powers held by the Director-General of Health.

New Zealand police are responsible for the maintenance of law and order during an emergency, the National CDEM Plan 2015 says.

They may exercise special powers during a state of emergency, and will liaise with other agencies to ensure the most effective use of police resources.

In comment provided by the Science Media Centre, Professor Andrew Geddis from University of Otago, said:

"With the declaration of a state of emergency and issue of an epidemic notice, New Zealand's government has taken on powers that haven't been seen since the 1951 Waterfront dispute.

"The police (and the army, if needed to support the police) are empowered to order any person to stop any activity that contributes to the current emergency - essentially, spreading Covid-19 in the community. Government ministers may set aside virtually any legislative provision that becomes impracticable to apply while the epidemic is in force.

"These give the state extraordinary reach into our lives, and transfer extraordinary power to the executive branch. They are a marker of just how severe the threat that this virus poses to us all."

- By RNZ