Artesyn Technologies at Youghal in County Cork is to close its manufacturing facility with the loss of 160 jobs.
Workers at the plant were told by management yesterday that the facility would be closed on a phased basis over the next nine months.
The American multi-national telecommunications company is to retain its sales and design offices in Youghal which employ 82 people.
The company's director of European operations, Philip Whelan, said the decision to close was one that management had worked hard to avoid, but it had no choice in the end because of the state of the telecommunications industry worldwide.
The layoffs will start on a phased basis in the New Year following negotiations over terms and conditions with SIPTU.
* 99 jobs are to be lost in Co Monaghan between now and next March at CPV (Containers and Pressure Vessels) in Clones.
Local politicians have said the news is a devestating blow for Co Monaghan.