Nortel Networks is let go 150 workers at its plant in Mervue, Co Galway. Workers at the company were informed of the redundancies in a meeting with management this lunchtime.
The company also announced a further 115 jobs will be lost at its operation in Belfast. The Canadian telecommunications giant already employs about 1,580 staff at plants in Belfast, Galway and Dublin.
A spokesman for the company told ireland.com the cuts were part of a worldwide restructuring programme designed to restore the company to profitability.
He said the decision to cut the workforce in Ireland was "an extremely difficult one to make".
He said the company had entered into a consultative process with the workers in order to minimise the impact of the job losses.
Following poor financial results earlier this year the company said it would cut its workforce worldwide by 20,000, revising the figure up from 15,000.
Nortel plans to reduce its worldwide workforce to 45,000 people and sell off non-core businesses which employ a further 10,000 people.
The company expects to post a net loss of $3.6 billion for the third quarter and intends to take further steps to adjust its business to the global telecom market.
The company already shed 40 jobs at its Galway plant as part of its February decision to cut staff worldwide.
The expansion of the company's research and development base in Galway, announced earlier this year, will not affected be by the cuts.
