Aer Lingus has warned cabin crew that they face being suspended from next week if they do not implement controversial new rosters.
The trade union Impact, which represents cabin crew at the airline, has signalled that the removal its members from the payroll could lead to a disruption of flight services.
In a letter to staff earlier this week the company said that failure to implement a new roster due to come into effect on January 17 would place cabin crew in breach of contract.
"Aer Lingus will not accept staff refusing to carry out some or all of their contractual duties. A continued refusal will result in you being put off duty and removed from the payroll".
The issue of rosters has been a major source of contention at the airline over the past year on foot of reforms introduced as part of a financial recovery programme at the airline known as Greenfield.
Cabin crew have been engaged in a limited, but gradually escalating, work to rule for the past several months as part of a campaign against new rosters.
Impact said that while cabin crew at the airline had accepted the requirement in the Greenfield agreement to increase flying hours to 850 per year, they had not voted to accept the roster changes had management had imposed last summer and those which it was attempting to impose from next week.
In a letter to Aer Lingus management, Impact national secretary Matt Staunton said: "We have informed our members that their employment contracts are protected under the industrial relations legislation, with which they and their union are fully compliant"
"You are well aware that Impact's industrial action campaign, which has produced little or no disruption to passengers whatsoever, is legitimate and legal under the industrial relations legislation. It will remain in place until this dispute is resolved to our members' satisfaction."
Mr Staunton said that that the potential disruption to passenger services implicit in the company's threat to remove cabin crew from duties represented "a misguided attempt to put pressure on the state industrial relations dispute resolution service" in advance of scheduled meeting at the Labour Relations Commission today.
It is understood that the hearing at the Labour Relations Commission was inconclusive.
"Unlike your threat of removing staff from duties, nothing in the ongoing and low-level IMPACT industrial action will have the effect of disrupting flights. This is clearly the case because there has been practically no disruption on foot of the action, which has now been in place for a number of months".
An Impact spokesman said this afternoon that any disruption to flight services at Aer Lingus would be as a result of any suspension of staff rather than due to industrial action.