SIPTU has appealed to the Minister for Enterprise, Trade and Employment to intervene to prevent the closure of the WOCO industrial components plant at Carrick-on-Shannon, Co Leitrim, where 117 people are employed.
The call to Ms Harney comes after management announced it was not prepared to negotiate with workers over the terms it says are essential to keep the plant open. These include increased productivity without extra pay.
Management says the adverse exchange rate between the pound and the deutschmark gave rise to the decision to close.
The plant is one of the country's biggest, and IBEC has been involved in attempting to broker a deal between management and workers.
According to SIPTU the company "is determined to close the plant" with plans to lay off 30 staff immediately.
"We are available at all times to enter into discussions towards resolving the current impasse, but this cannot be achieved if the company remains unwilling to negotiate," said a statement.
The company's parent announced its intention to close the plant on September 17th, but after consultation with local management it was agreed it would consider keeping the plant open for a three-month evaluation period.
As part of this arrangement, workers would have to agree to the pay terms and what management calls "multi-machine operations", a reference to work practices at the plant.
A meeting of workers has been called this Saturday to discuss the plant's future.
Workers will be told that management is using them as an excuse to close the plant.
In the past, management has denied this charge although no one was available to comment last night.