SIPTU members at Bausch+Lomb in Waterford will begin work stoppages tomorrow over a pay dispute.
The union has accused management of "intransigence" over negotiations for a pay rise for workers at the multinational.
It comes as Bausch+Lomb has warned employees at its Waterford factory that the "long-term sustainability" of the plant is in danger if a pay dispute is not resolved.
SIPTU organises over 1000 workers employed in the manufacturing plant which produces contact lenses and other pharmaceutical products, as well as providing research and development and surgical support facilities.
It's organiser Allen Dillon, said: “This dispute is the result of management intransigence in relation to providing an adequate pay rise for workers in this highly profitable company.
"These workers need to achieve a pay increase that protects their standard of living and purchasing power. As with workers across the economy they face a cost of living crisis resulting from an inflation rate which is at its highest in a generation and soaring costs for other essential services.”
He added: “These workers are seeking to reach a reasonable pay agreement that recognises the sacrifices they have made over recent years to ensure the continued success of this plant. The campaign of industrial action will begin with the first in a series of two-hour work stoppages on Saturday during which pickets will be placed on entrances to the plant.”
Management told staff this week that if industrial action proceeds, "our plans for growth [may be] impacted negatively", urging them to accept a deal.
The action comes after the breakdown in talks held at the Workplace Relations Commission on Tuesday, where pay, bonuses, sick pay and the length of the working week were discussed.
The WRC talks took place to avert any industrial action, after staff who are members of trade union SIPTU voted overwhelmingly for strike action last April.
Industrial action, which would include work stoppages, workers not covering certain jobs at the plant and not being available for overtime, was also supported by members in the April ballot.
The vote was held following the rejection of a three-year deal worth 8.25% as recommended by the Labour Court.
Workers are understood to be unhappy at the rate of pay compared to others in the pharmaceutical manufacturing sector, while the dispute is also partly linked to pay cuts taken in 2014 to stave off job losses at the company, which saw a wage reduction of 7.5% in basic pay and the elimination of some bonuses. It also meant one hour of work added per week to their roster.
In the company's letter to workers, which many received yesterday, Site Lead Mark Hennessy said Bausch+Lomb is "committed to finding a resolution" but "not at any cost".
"We must remain competitive and protect and current future employment and the long-term sustainability of the Waterford site," he said.
"We don't wish to see the future of Bausch+Lomb and our plans for growth impacted negatively, however we do feel it important to inform you, as a valued member of our team, that industrial action, may do just that."
In a statement issued to media, a spokesman said the company's offer to workers was fair, adding they "should be considered favourably in the wider context of the present economy" along with the company's investment in Waterford.
"Since 2015 together we've grown our facility by 600 people and we have some of the most competitive salaries in the South East region comparable in our industry," he said.
SIPTU Sector Organiser, Neil McGowan, said commitments were made by senior management in 2014 that workers would share in the profitability which resulted from improved efficiencies at the plant.
"We have yet to see an offer from the company that lives up to this commitment," he said.
It announced plans to invest €90m to expand its facility last summer.
The 2014 deal included an improved redundancy package for 200 workers who lost their jobs as part of management's plan to secure the long-term viability of the company.
In 2016, SIPTU members voted through an improved pay deal which saw salaries increase by 9.5 per cent over a three year period.