Siptu is seeking an "urgent meeting" at the Labour Relations Commission to discuss today's announcement by pharmaceutical giant Pfizer that 180 jobs would be lost at its manufacturing plant at Little Island, Cork.
The union's sectoral organiser Alan O'Leary described the news as "a major blow to Cork and the Munster region".
Mr O'Leary said the announcement last month that negotiations had ended with a third party over the potential sale of the plant had "sent alarm bells ringing".
In a statement issued this afternoon, Mr O'Leary said: "The effects of these major job losses will be felt mostly by the workers and their families, many of whom have had financial worries since the Pfizer sell-off announcement last year.
"Now these workers, many of whom were employees of Pharmacia & Upjohn and, before that, Gaeleo, face the prospect of seeking employment in a declining jobs market. It is a bleak day on the jobs front for Cork."
Mr O'Leary said the union would now seek an early hearing at the Labour Relations Commission hearing to assess the full effects of the "shock announcement".
"We also remain concerned at this point regarding the sale process of Pfizer's other plant in Loughbeg, Ringaskiddy, County Cork. This process is at a very sensitive stage therefore it would be unhelpful at this stage to speculate publicly until this process is concluded”, Mr O'Leary said.