Management at the UNIFI textile plant in Letterkenny, Co Donegal, has confirmed the closure of the company.
Three hundred jobs will be lost when the factory shuts at the end of October.
Bosses blamed cheap foreign competition and profit losses for the decision to close the plant.
Last night, the US-based Chairman and Chief Executive of UNIFI, Brian Parke, said it was a very difficult decision but a necessary one.
The Chamber of Commerce in Letterkenny estimates that the closure will cost the area around €25 million a year in lost revenue.
It has called on the Tánaiste and the Minister for Employment, Mary Harney, to make finding replacement jobs her top priority.
Earlier, Ms Harney expressed her hope that those workers who will lose their jobs will find work elsewhere in the town.
Speaking to RTÉ, she said she was disappointed that the plant was to close, but that there were companies in Letterkenny looking to employ workers.