Speight's Brewery in Dunedin has been shut down and there may be some temporary shortages of stock, following a cyber attack on parent company Lion.
The attack took place on Monday, and investigations to date show the system outage was caused by ransomware — where computer hackers seize control of data or systems, then demand a ransom that often runs to millions of dollars.
A Lion spokeswoman said the company immediately shut down key systems as a precaution, and confirmed production at the Speight's Brewery had stopped temporarily.
She said the cyber attack had had a significant impact on the Lion's and Speight's brewery operations, namely their supply and distribution.
"Our teams are working as hard as they can to service customers and suppliers, implementing new manual processes and investigating all alternative options."
IT teams and cyber advisers were "working around the clock" investigating the issue and assessing how long the impacts would continue, she said.
"We are working hard to resolve this incident as quickly as we can so we can return to full production and get our products flowing back into the market.
"This is taking some time, but it is necessary that we work through this properly."
There was no evidence that any of the information contained in the Lion computer system had been affected, but it was something the company would be reviewing closely.
She said it would be "premature" to speculate on how much the attack had cost the company, but the timing of the attack could not have come at a worse time.
"Throughout the Covid-19 shutdown, we were able to continue to brew beer safely.
"We had stock at hand and were gearing up to increase brewing ... This attack has delayed those plans, and because of the situation we have limited visibility of our products.
"We're working to bring our breweries back online ... In the meantime, we will be managing our stock levels very closely and may see some temporary shortages."
Outside of Speight's, it is not known what other Lion brands' could face stock shortages with disruption to production.
The Herald has contacted Lion for further comment.