"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 group said it had put in additional safety measures in place to ensure the safety of its staff during this time.
"We are working with New Zealand's two major supermarkets to submit to government personal protection equipment requirements and supply for our people. 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," it said.
"We will continue to evolve our protection protocols for our team members and we are well aware that as one of the largest New Zealand employers, with 12,000 employees, the Group's ability to keep its Warehouse brand and Group fulfilment centres open, not only helps customers with key essentials but it goes some way to ensuring the sustainability of the business for communities, customers and stakeholders."
Retail NZ chief executive Greg Harford said the industry group was still working through what types of retailers constituted an essential service and therefore who would be able to remain open during the lockdown come Thursday.
He said he was not aware of any provisions that had been made to allow The Warehouse stores to remain open during that time.
"It doesn't accord with the advice that I have seen coming out of Government."
First Retail Group managing director Chris Wilkinson said it was "inappropriate" that The Warehouse stores would be able to remain open while similar stores would have to close.
"If The Warehouse is [able to] open then by rights Briscoes almost certainly should be open, and if Briscoes is open, where does that place the likes of Mitre 10 Mega and Bunnings who are also very strong [sellers] of resilience products," Wilkinson told the Herald.
"This creates an unfair playing field for other businesses who are all trying to do the right thing - this has come from left field, wasn't anticipated. All of the big retail brands just want a fair and even playing field."
Wilkinson said he anticipated that the Government would "revisit" the decision about what retailers could and could not operate during the lockdown period.
Retail NZ is calling for the Government to issue clear guidance on what businesses and retailer-types will be able to remain operational during the lockdown.
