The Gallaher Group is to close its Dublin cigarette factory with the loss of 200 jobs.
The Tallaght-based operation will shut down over the next seven months after an international management review of its European operations.
The 121 direct employess and 80 contract catering and cleaning staf will be briefed by management later today.
SIPTU have called for an urgent meeting with the Tanaiste Mary Harney and the international management of Gallaher.
They have also called on support from all public representatives to ensure that the workers' rights are secured.
Speaking after the announcement, SIPTU branch secretary Anne Speed said: "This decision will mean almost 200 workers losing their jobs and joining growing dole queues".