Aer Lingus says it may take disciplinary action against staff who staged an unofficial one-hour work stoppage last Saturday.
Aer Lingus chief executive Dermot Mannion says staff's pay will be docked. Photograph: Bryan O'Brien
Some 100 clerical staff stopped work for around an hour at 6am in protest at being asked to work on check-in desks and at boarding gates.
The airline was not given any prior notice about the stoppage which caused delays for thousands of passengers scheduled to travel on early-morning flights.
In a letter sent yesterday to Siptu president Jack O'Connor, Aer Lingus chief executive Dermot Mannion said the pay of all staff involved in the stoppage would be deducted for the period of the stoppage.
Mr Mannion also informed Siptu that the company would launch an investigation into the stoppage, which could lead to disciplinary action being taken.
Aer Lingus and Siptu are currently in negotiating the airline's proposed changes to work practices in a bid to achieve cost savings of €20 million a year.
In a separate letter to Siptu's national industrial secretary Michael Halpenny, Mr Mannion set a deadline of August 1st for the implementation of these cost cutting measures.
Siptu said it would reply to Mr Mannion's letters today. The union also said the stoppage by its members last weekend had not been sanctioned by the union.
The Dublin Airport Authority, which is expecting more then 90,000 people a day to use the airport in the coming weeks, expressed concern about the dispute.