A company that makes smart meters for British Gas is planning to shed 288 of 601 jobs at its factory in Greater Manchester because of Brexit.
Landis+Gyr told the GMB union it could move production from Stockport to Romania and Asia because costs have risen 20% since the referendum in 2016.
The union said it was “an example of the pressures companies are facing due to Brexit uncertainty”.
A consultation on redundancies is expected to finish by the end of April.
Landis+Gyr wants to make 266 manual roles, 19 technical posts, two managerial roles and one professional post redundant.
GMB hopes to reduce those figures.
Organiser Shaun Buckley said the Swiss company had cited a 20% increase in production costs, in part due to the weak performance of sterling against the euro.
Moving production to Romania and Asia would also mean Landis+Gyr could offer workers a fifth of UK wages, he said.
“The decision to move manufacturing abroad is catastrophic news for GMB members at Landis+Gyr and their families in Stockport.
“GMB will be working tirelessly to secure the best possible deal for affected members during consultation.”
Landis+Gyr said the consultation process would “examine means of optimising the production costs” of its UK smart meters.
A spokeswoman said: “We place great value on our staff and are committed to conducting the consultation process in an open and collaborative fashion.”
A consultation on redundancies at its factory in Market Deeping, Peterborough is also under way.