It follows a review of operations in Ireland and the UK
SIPTU claims workers at the C&C bottling plant in Tipperary found out through the media that they were to lose their jobs.
News broke this morning that 140 staff are to be made redundant at the site in Borrisoleigh as part of cost-cutting plans.
The firm, which is attempting to save €15m a year, will also shut a base in Sommerset in the UK.
SIPTU organiser Terry Bryan says their union members are unhappy with second-hand information, and want a meeting with management as soon as possible.
These locals told TippFM were shocked to hear of the closures.
This follows a comprehensive year-long review of the company's operations in the UK and Ireland.
It is understood the group intends to close its water bottling plant at Borrisoleigh in Tipperary, where it employs 140 staff, and its cider-making plant at Shepton Mallet in Somerset, South West England.
Some of the closed production facilities will transfer to C&C's main facility at Clonmel, Co Tipperary where an additional 80 jobs are expected to be created.
C&C - which owns the Magners, Bulmers and Tennents brands - has been experiencing challenging trading conditions, particularly in the US, where it purchased a cider production facility in New England three years ago.
The company's operating profits fell by 9.5% to €62.6m in the six months to September 30th of last year.