More than 134 people are to lose their jobs after the decision by a Dundalk-based firm to move its production to China.
Electronic components manufacturer Littelfuse said the factory would be closed in stages over the next two years.
Louth TD Fergus O'Dowd said he was dismayed at the news and blamed the state's high cost base for driving jobs abroad.
"While there has been some welcome news recently regarding job creation in Louth, the last 18 months has seen several factory closures across the county," said the Fine Gael deputy.
"For the Littlefuse workers, the news today that yet more of the county's jobs are to relocate to China will be an extremely bitter pill to swallow."
Labour representative for Louth, Cllr Ger Nash, called for urgent Government action to stem the flow of manufacturing job losses across the economy.
"This plant has been in operation for years, and these job losses will be felt all across the county," he said.
"Unfortunately this closure is part of a pattern we see emerging in Dundalk and across the country, where industrial plants are closing down, with jobs being lost to low-wage economies."
Employees and union representatives have been informed of the closure.