One of Auckland's confirmed cases of COVID-19 was employed at Americold, a frozen storage warehouse which handles imports from overseas.

Managing director Richard Winnall told Newshub the man had been sick for quite some time before testing positive.

"He's been on sick leave for the last nine days, been off with flu symptoms," said Winnall.

"He of course didn't test positive until quite recently."

Winnall confirmed all of Americold's employees at the Mount Wellington warehouse had been sent home and would be tested for COVID-19. The company's warehouse near Auckland Airport has also been closed.

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"There's little indication of a case there, and no one has any symptoms but it's a precaution due to the geographic location," he told Newshub.

Some studies have indicated COVID-19 could last longer on cold surfaces however Winnall said he was not aware of this.

"We've seen no evidence of longevity of the virus [in cold temperatures]," he said. 

He said any goods handled in the warehouse would not be touched by consumers as the packaging is multilayered. 

Americold has 183 warehouses across New Zealand, the US and Australia.