Don't expect to be able to go down to your local Warehouse during the four week lockdown, Prime Minister Jacinda Ardern says.

In an announcement to the sharemarket on Tuesday morning, The Warehouse said it was a provider of key consumer goods for New Zealanders and its 92 Warehouse stores and distribution centres would remain open.

"In the past two weeks the group has seen unprecedented demand for essential items across all our brands. Goods sold included essential items to prepare themselves for the mandatory isolation period of at least four weeks," the retailer said.

At a press conference on Tuesday afternoon the prime minister said retail outside of supermarkets was unlikely to be considered an essential service.

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"An essential service is something required to maintain their own health and well being, get food and the necessities of life, that we can maintain our response to Covid-19 and we can maintain public health and safety," Ardern said.

Shares for The Warehouse Group initially rose on the announcement, but at 1.49 pm a trading halt was placed on the company..

In a second announcement to the stock exchange at 3.42pm it said there was considerable uncertainty around what meets the definition of essential businesses "and which products and services they are able to provide".

It said it was in talks with government on which categories The Warehouse might still be able to sell once New Zealand goes into level 4, and expected to make another announcement on Wednesday.

Ministry for Business, Innovation and Employment (MBIE) chief executive Paul Stock said earlier on Tuesday afternoon it had not made a decision on individual businesses, and companies should be careful about making announcements before receiving official confirmation.

"We expect New Zealanders, firms, businesses, and people to assist in the self isolation process, not to assume they are an essential service when they are not," Stock said.

The Government had identified 15 sectors that are considered to be essential services.

A list could be found at covid-19.govt.nz and would be updated regularly, he said.

From 5pm Tuesday, there would be an 0800 number where firms can call in if they are unclear about their essential service status, Stock said.

"My suggestion is that if you are in doubt about whether you are an essential service, then you are probably not," he said.

A petition was launched via change.org calling on the Government to close The Warehouse while the country was under isolation.

ALDEN WILLIAMS/STUFF The Warehouse's 92 stores will stay open during the coronavirus lock down.

The Warehouse statement said the retailer would implement new safety protocols across its 92 stores to protect staff and customers, including additional cleaning, leave and wellbeing support.

"We are working with New Zealand's two major supermarkets to submit to government personal protection equipment requirements and supply for our people," the statement said.

"Customers in store will be asked to adhere to new protocols including social distancing and limiting purchasing, in some cases, to two items per product."

The other stores in The Warehouse Group, including Torpedo7, Noel Leeming and Warehouse Stationery would be closed but the company's online store and fulfilment centres would continue to operate, the company said.

The Warehouse had already implemented limits on high-demand products such as toilet paper, hand sanitiser and face masks.

During the level 4 lock down, most retailers will be closed.

Supermarkets have been given special dispensation to remain open with some altered conditions.

This included reduced hours, face masks for staff and perspex at the checkouts.

The major supermarket chains, Countdown and Foodstuffs, have continued to call on New Zealanders to shop normally during the lockdown period.

The Warehouse has been approached for comment.