230 jobs are to be lost at the Volex Electronics Components plant in Castlebar, Co Mayo.
The company says the redundancies are part of a rationalisation programme which will also see the closure of a sister plant in Manchester.
Workers leaving the factory this evening said they had been expecting some job cuts, but were shocked and disappointed at the scale of the redundancies.
A spokesperson for Tanaiste Mary Harney said the priority for the state development agencies will be to do everything possible to find alternative employment for those now out of work as a result of today's announcement.
FAS will also engage with the workforce with a view to carrying out a skills audit and offering retraining where needed.
Volex, which has been in production in Castlebar for the last 15 years, employed 970 workers at peak periods. As a result of today's announcement the Castlebar workforce will be cut to 250.
170 jobs are to be lost at the Volex plant in Manchester. Castlebar will now become the company's European operation headquarters.
Managing Director John Corcoran said the company regretted the job losses but the decision would consolidate the future of the Castlebar plant.
Volex is a UK owned company which manufactures cable harness for the telecommunications industry.
