Union officials say General Motors is cutting up to 600 jobs at its assembly plant in Ingersoll near London.
A spokesman for Unifor Local 88 says the layoffs will take effect in July at the CAMI Assembly plant.
The union says the move was announced this morning and is directly linked to the company's decision to shift production of the G-M-C Terrain to Mexico, where labour is cheaper.
Unifor National President Jerry Dias says the decision comes out of left field.
"This is NAFTA at its worst," says Dias. "This is exactly of what we've been talking about. This is the straight exodus of good Canadian jobs to Mexico and at some time or another we're going to have to put a stop to it."
G-M did not immediately reply to a request for comment.