Cigarette company Gallahers is to lay off 121 workers and cease manufacturing at its Dublin plant and cut a further 175 jobs at its factory in Co Antrim.
The factory at Airton Road, Tallaght, will continue to carry out activities such as distribution and marketing, a spokesman said. Manufacturing will be moved to Ballymena, Co Antrim, where 130 will be cut this year and 45 over the next two years.
A further 85 workers in Austria are set to lose their jobs as part of restructuring with the remainder of the cuts being spread across the group.
The job cuts were announced following an international management review of the company's operations.
The announcement by the company, whose main brands are Silk Cut and Benson & Hedges, has caused shock and anger among workers and trade union officials who claim they were not consulted about the decision.
SIPTU claimed the Tallaght facility would close with the loss of 200 jobs, a claim rejected as untrue by the company.
Ms Anne Speed of SIPTU said her union has yet to examine the outcome of Gallaher's management review but is "very conscious of the serious disregard for the rights and interest of employees and stakeholders in international companies".
She continued: "While IBEC commits itself to national agreements - recognising the trade union members as stakeholders - international managements bypass their obligations, undertake reviews and obliterate employment with little or no direct consequences for their actions".
Ms Speed said SIPTU will be seeking an urgent meeting with the international management of Gallaher's Dublin and the Tánaiste, Ms Harney, to consider the fallout of this announcement.