SIPTU workers at the Liebherr manufacturing plant in Co. Kerry have rejected Labour court proposals which would have seen a 2.5% pay increase backdated 21 months.
An industrial dispute is threatening the operation of the large plant which employs 670 people in Killarney.
The Minister for Jobs Richard Bruton has appealed to both sides to find a resolution.
SIPTU represents about 300 of the crane manufacturing plant's workforce.
The Union's Industrial Organiser Marie Kearney says they're available for direct discussions with Liebherr.
"The company has invested €50m in the last four years in upgrading the plant with new facilities - which we welcome," she said.
She said they had asked the company to invest in the workers equally, who had helped to create €63m in profits.
"The Labour Court acknowledged in its recommendation that there had been minimal face-to-face negotiations … we're available for direct discussions."