The parent company of Tara Mines in Co Meath has warned that a protest by workers at the facility could jeopardise plans to safeguard the operation.
Boliden Tara Mines has called on staff to suspend their action.
Workers at the mine are staging the protest over plans to temporarily close the facility and are accusing the company of refusing to engage in meaningful negotiations.
The demonstration began yesterday evening and has continued into today.
Last month, Boliden announced plans to suspend operations at the mine and temporarily lay off 650 workers.
The temporary closure is scheduled to commence on 14 July.
The company said financial losses at the mine have been driven by several factors including a decline in the price of zinc, high energy prices, general cost inflation and operational challenges.
Boliden said it was acutely aware of the difficulty and disruption that the decision to temporarily suspend operations has caused for employees.
"Since the protest action has commenced, we are very concerned that essential maintenance, required to safeguard the operation, is becoming increasing difficult to perform," the company said in a statement.
It added that it will attend talks with the group of unions at the Workplace Relations Commission tomorrow.
A spokesperson for the Department of Enterprise, Trade and Employment said it is imperative that the company and the unions fully continue their engagement with each other at the Workplace Relations Commission.
"While the concern and frustration of workers at Tara Mines is fully understandable, unofficial industrial action by a small group of workers will not help the situation and Minister Coveney urges those involved to allow the WRC do its work," the spokesperson added.
Unions passed an emergency motion at the ICTU Biennial Delegate Conference in Co Kilkenny this morning, calling for an immediate and major intervention by the Government to protect the continued operation of Tara Mines.
"This will not be resolved without the Government taking ownership of this situation and saving this critical asset," SIPTU Division Organiser Adrian Kane said.
