Mining group Arcon has put 200 workers at its Galmoy zinc mine in Co Kilkenny on protective notice in a dispute over pay and conditions.
In a statement, Arcon said the move followed an overtime ban by unions. The ban was introduced after a breakdown in talks over a new wage deal.
The company said the impact of the ban on production levels, coupled with the low price of zinc and weakness in the value of the dollar had led to unsustainable losses.
If the overtime ban is not lifted, the mine may have to cease production, Arcon warned.
SIPTU branch secretary for Kilkenny, Mr Bill Mulcahy, said workers had not received a pay rise in two and a half years and were entitled to an increase. With zinc prices at a two-year high, Arcon's insistence that it could not afford to do so was disingenuous, he said.
The group reported a net loss of €14.7 million in 2002, an improvement on the €15.6 million loss in the previous year.
The majority shareholder in the company is Independent News & Media executive chairman Sir Anthony O'Reilly.