ALMOST 700 jobs are on the line after management at Tara Mines placed staff on protective notice.
Last Thursday, two days after returning from their Christmas break, workers at the zinc mine were told of the decision.
SIPTU, which represents 400 of the employees, said the move followed discussions with the company which is seeking a 10pc cut in wages as well as reductions in overtime and bonuses.
The mine, near Navan, Co Meath, is owned by Swedish firm Boliden which bought it in 2004 and is one of Meath's biggest employers.
Tara, which began production in 1977, is the biggest lead and zinc mine in Europe and the fifth largest in the world.
Fine Gael TD Damien English, who has offered to help in the dispute, said: "There have been problems on many occasions in the past at the mine, and they always managed to be resolved. We can't let this be any different.
"Tara Mines is a massive employer in Navan and Co Meath and there are hundreds more jobs involved in the spin-off services."
SIPTU organiser John Regan said the union has asked the company to refrain from proceeding with the cuts before a case is made to the Labour Relations Commission.
The commission is due to hear the case on Wednesday, but Mr Regan said it was unclear if the sitting would take place because he has yet to secure a mandate to negotiate. The protective notice is being reviewed on a daily basis.
Any decision to close Tara Mines would have a massive impact on businesses in the town and county.
Local Fianna Fail councillor Tommy Reilly has described the threat as a "crisis" and said that "all hands should be on deck" in seeking a solution.
"The closure of Tara Mines would deal a devastating blow to Navan. Tara Mines is one of the last remaining major employers in the county," he said.
"God knows the town has suffered enough with over 1,000 job losses in the past number of years due to the closure of Navan Carpets, Crannac and Spicer's bakery."
Mr Reilly said he understood there had been a number of significant ore finds at the mine in the past six months which would extend its life by perhaps 20 years.
Tara currently employs 670 people including support and administration staff and drivers.