More than 200 jobs are to go at the German-owned Amann specialist textile plant in Tralee.
Employees were told 210 jobs were to go as they met with management at lunchtime. This follows the announcement in January that 120 jobs were to be transferred to other Amann group facilities in Romania and Germany.
Overall manufacturing costs as well as the ongoing recession was blamed for the cut.
Amann, which employs 340 people, manufactures high quality technical sewing threads for use in the automotive, clothing and fashion industries.
Workers at the Amann plant were told today that the remaining jobs at the plant will be gone by mid-2010 when the plant closes. It will transfer its operations to South Asia and China.
Siptu branch organiser Con Casey said the effect of the closure would be "catastrophic" in North Kerry.
"This is a company where whole families have been employed and they will now find it next to impossible to find alternative employment.
"There is an urgent need for the Government to come up with a strategy to save manufacturing jobs before it is too late. The sector has virtually collapsed here and overall unemployment has risen by 70 per cent in the past year."
Siptu is to meet management on Monday to discuss redundancy arrangements.
Amann was established in Tralee in 1998 after buying the former Klopman textile plant, in what was then a major jobs announcement for Tralee by then Tánaiste Mary Harney.
The news has been described as a "devastating blow" to the region by Fine Gael's Kerry North representative, Jimmy Deenihan, who compared the plant to Dell in Limerick.
“This is terrible news for the people of Tralee and the surrounding area and there will be very grave economic consequences for other businesses in the town," he said.
"The news that the plants equipment is to be moved to Amann's operation in China is a further reminder of how uncompetitive Ireland has become in recent years – and in this case Tralee is paying the price."
Fianna Fáil TD Thomas McEllistrim called on the IDA to redouble its efforts to bring fresh investment to Tralee. “This really is terrible, terrible news for the workers of Amann and their families . . . and I hope the company will put a generous redundancy package in place to see them through this difficult time.
“It is the least they deserve after all the loyal service and hard work they have done for Amann over the years.”
Labour Party spokesman on enterprise and employment Willie Penrose said measures were needed to tackle the jobs crisis.
"My thoughts first and foremost are with those workers who have learned today that they are to be made redundant, particularly in an economic environment where it will difficult for people to get back on their feet in the short term," he said.
Mr Penrose said the Back to Education and Back to Work Enterprise allowance schemes should be reformed to
ensure that jobseekers can avail of these supports within a few months of losing their job.
"We should also be looking at creative ways of promoting career breaks, and flexible work options particularly in the private sector," he said.