Up to 362 people are expected to lose their jobs after the owners of Dunedin's iconic Cadbury factory announced on Thursday they are shutting down production.
Cadbury is the fourth largest employer in Dunedin, and its closure has taken many by surprise.
"There'd been a lot of investment in the Dunedin site and we believed that they were doing very well," said Chas Muir, industry coordinator for the food sector of E tū Union.
"We had no concerns - this is straight out of the blue. We weren't expecting it at all."
Mr Muir told Newshub he expects 400 unionised employees, both full-time and seasonal workers, would eventually lose their jobs because of the closure.
"This is a massive blow - not only for those workers, for whom it will be devastating, but also for the Dunedin economy."
American multinational Mondelez International told staff on Thursday morning it would halt production at the Dunedin site in early 2018, shifting it to existing sites in Australia.
Most production will be transferred to a factory in Melbourne.
Dunedin's Cadbury factory has been operating for more than 80 years and 70 percent of its products are exported, mainly to Australia.
Local Labour MP Clare Curran says she feels for the people who will be affected.
"This is shocking news and Labour will be a strong voice for the working people of Cadbury as they face an uncertain future.
"Closures like this affect whole communities. Employment changes affect mortgages and schooling choices. It is too soon to grasp the flow-on effects, but we can be certain this will have a huge impact across Dunedin."
Owners Mondelez International says the first phase of redundancies will take place late in 2017, with approximately 100 people remaining with the business until early 2018.
"This is an incredibly difficult announcement, given the factory's proud history and the outstanding performance of our employees," said area vice-president Amanda Banfield.
Dunedin's popular tourist centre Cadbury World - which attracts more than 110,000 people each year - will stay open.