Aer Lingus has threatened to stop recognising Siptu staff representatives unless they "commit to professionally discharging their responsibilities" or are replaced.
he airline's management made the threat as a row over work practice changes on the ramp at Dublin Airport escalated after the union pulled out of a meeting with chief operating officer Mike Rutter.
"Given that staff representatives have refused again to meet senior management, we will deem their non-attendance as confirmation that they do not wish to continue representing colleagues," wrote Aer Lingus director of employee relations and change Sean Murphy.
"Therefore we would ask that Siptu and the representatives reflect on their position over the weekend.
"If the position remains the same, with effect from close of business Monday, we will withdraw the facilities provided to the representatives until such time as they commit to professionally discharging their responsibilities as representatives, or are replaced."
The trade union had written to the airline insisting it withdraw "unsubstantiated" allegations that its members were involved in interference with new digital devices designed to improve efficiency on the ramp at the airport.
Murphy claimed "a clear pattern of behaviour is developing" and it was "absolutely astonishing" they had again chosen not to meet "the senior management team of the company they work for, who pays their salaries and provides them with the facilities to conduct the business of a staff representative".
"It is totally unacceptable that such disregard and disrespect is being shown to the senior leadership of Aer Lingus," he wrote.
An Aer Lingus spokeswoman said the airline had subsequently met staff representatives last week and "this engagement was constructive", with two further meetings scheduled next week.
"We hope that these talks will be productive, as there is huge potential and opportunity for our colleagues in this airline as we continue to grow and expand," she said.