Around 70 jobs are at risk at the Cadbury factory in Coolock, North Dublin.
Mondelez are understood to have briefed trade unions this morning about plans to restructure the plant which has been in operation for over six decades.
They currently employ 380 people in the north Dublin plant with up to a fifth of the workforce expected to be lost to the restructuring plan.
Voluntary redundancies are understood to be involved in the plans which will take place over the next two years and see the company invest €15 million in new technology.
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Trade union SIPTU says its members are "deeply unhappy" with the plans, and it intends to meet with management next week over their "unacceptable approach".
SIPTU organiser Colm Casserly said: “Our members are deeply unhappy with the announcement by management this morning (Thursday, 9 May) that it is seeking 70 staff redundancies.
“We are currently consulting our members prior to a meeting with management, which will take place at the earliest opportunity next week.
"At this meeting, SIPTU and Unite representatives will make clear our members’ position and seek to minimise the number of job losses at the plant.”
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In 2016, workers at the plant went on strike as Mondolez proposed outsourcing a number of jobs.
It followed the closure of their Tallaght production plant in 2014, when 45 jobs were lost.
Mr Casserly added: “Workers at the plant have, over recent years, agreed to the major restructuring of operations and changes in work practices.
"In light of this the current approach of management is unacceptable and once again raises fears concerning its long-term commitment to this plant and its workforce.”
