It has been confirmed that 199 jobs are to go at the Covidien medical devices manufacturing plant in Co Offaly.
Staff at the plant in Tullamore were informed of the cuts at a meeting with unions and management this afternoon.
The redundancies are made up of 160 permanent full-time staff and 39 temporary staff. They will take effect from September.
Workers have been offered six weeks of pay per year of service plus their statutory entitlements.
Covidien said a staff reduction is needed to ensure the long-term viability of the operation.
Workers were told that declining sales and increased competition from low-cost producers are the primary reasons for the job losses.
The company said it had exhausted all other actions before announcing the job losses.
It says the terms of its early retirement and redundancy programme will ensure all redundancies will be voluntary.
Following this afternoon's briefing, staff said they were shocked by what they had been told and many had not foreseen today's announcement.
SIPTU organiser Frank Jones said a period of negotiation and discussion with management would now begin.
The medical device manufacturing plant is Tullamore's biggest employer, with 650 people working at the plant.
Those employed in Tullamore are part of a 1,700 workforce for the company in Ireland, with its European Operations area headquartered in Dublin.
The firm said this evening it is to invest €3m in Tullamore this year and is committed to the Midlands town.
The Taoiseach has said the announcement of job losses is disappointing but that the CEO of the firm had assured him that the redundancy plan is the best way to protect the remaining positions.
Mr Cowen said it was a difficult time for the employees and their families but said demand for the firm’s medical products remained healthy.
Speaking to RTÉ, the Taoiseach said the Government had to keep working with State job agencies and said he had spoken to the head of the IDA this afternoon.
Criticism of IDA's performance
Meanwhile, the President of the Midlands Gateway Chamber of Commerce, Dominic Doheny, has criticised the IDA for failing to target job creation in Co Offaly.
Mr Doheny, who heads up the regional chamber representing the towns of Athlone, Mullingar and Tullamore, says the vast majority of foreign direct investment in the midlands has been in Athlone, with only a small number of jobs in the past number of years created in Tullamore.
Mr Doheny says state-of-the-art facilities available in Tullamore are empty and could be used to attract investment to the town.