The AO Smith Corporation in Bray is to close with the loss of 140 jobs. AO Smith makes electric motors.
A spokesperson for the company said the Bray plant had been operating at a significant loss for the past five years and a decision had been taken to move the work being carried out in the plant to China and the US.
SIPTU says the decision has come as a shock to the workforce, particularly as it had been in negotiations with the company about cost saving measures and believed the process was successful.
SIPTU blamed a 'corporate culture of relocating to eastern Europe for cheap labour' for the closure and said its priority now was to secure compensation for the workforce.
Meanwhile, 65 jobs are to go at Merops Nutrition in Ballymount in Dublin. The factory, which makes pet food, is expected to close by June 17.
