Australian owned telecommunications company TelstraClear is looking to cut 120 call centre jobs in New Zealand, moving the service to Manila in the Philippines.
The Engineering, Printing and Manufacturing Union (EPMU) condemned the proposal and said it believed 170 jobs would be affected.
TelstraClear told Fairfax's BusinessDay 120 jobs were under consideration, including 75 in Christchurch, but it was only a proposal at this stage.
TelstraClear spokesman Chris Mirams said the proposal was about better customer service but admitted it would also save the company millions of dollars.
"We've been making the case to keep these jobs in New Zealand since last November when TelstraClear said they were conducting a feasibility study into shifting their call centres offshore.
Today they told us they thought the case for going offshore stacked up," EPMU organiser John Kerr said.
"This is all about accessing so-called cheap labour overseas but comes at an enormous price for our members, many of whom are just starting out and have young families to support."
Kerr said the proposal did not even make good business sense as potential damage to TelstraClear's brand was enormous.