Aer Lingus is to begin an investigation today into a work stoppage at Dublin Airport at the weekend.
The company is expected to dock the wages of 100 ground staff who were involved in the action on Saturday morning.
They refused to work when they were asked to man check-in desks and boarding gates, resulting in flight delays of up to two hours.
Management at the airline has written to unions describing the action as 'totally unacceptable'.
However, SIPTU insists it was not an official dispute.