Imperial Tobacco is to close its Cadena cigar factory in Tallow, Co Waterford with the loss of 68 jobs.
The company said the sector is low-priced, highly competitive and sales are in decline.
As a result, it said, the Cadena business is not viable and unlikely to be in the future.
SIPTU said it was dismayed by the decision. Branch Secretary Ms Marie Butler said: "The workforce has worked exceptionally hard to ensure that their product - which is of the highest quality - was efficiently made, with a good cost base."
She said: "Unfortunately their efforts have not been sufficient to sustain these jobs."
She said the closure would have a major impact on Tallow and called for immediate intervention to ensure alternative employment can be found.
Workers at the company were informed of the decision today and a period of consultation has already begun.
Imperial Tobacco bought the Cadena cigar business in 1996. Most the produce made in Tallow is for the Dutch private label sector.
Meanwhile cigarette company John Player and Sons said the relocation of its Dublin factory to the west of the city will result in the loss of 45 jobs.
The company currently employs 200 people at its plant on the South Circular Road. The company said the rationalisation programme will be spread out over 2 years and it hopes that a sufficient number of its present staff may be interested in taking the early retirement package.
