The Irish Aviation Authority (IAA) has said it cannot rule out further delays to flights at Dublin airport over the weekend and possibly into next week, after unofficial action by air traffic controllers led to the closure of the airport to flights for an hour last night.
However, officials from the Impact trade union, which represents the controllers, were also engaged in talks with them late last night in a bid to avoid any further disruption.
The unofficial action, which led to the cancellation of all incoming and outgoing flights to Dublin airport between 10.30pm and 11.30 pm last night, affected some 30 flights during one of the airport's busier periods.
This in turn led to to delays of up to one and half hours, according to one airline.
Last night's decision by Dublin airport air traffic controllers not to engage in overtime is the latest development in an ongoing dispute with the IAA. Controllers claim that a shortage of staff has led to a system that is dependent on overtime.
Both sides met at the Labour Relations Commission (LRC)this week in an attempt to resolve the matter.
In order to facilitate the talks, the Impact members had agreed to "stand down" their unofficial action.
But it is understood that the decision to close the airport last night was taken after the IAA was informed yesterday evening that overtime cover for its control tower would not be provided.
Confirming its decision to close the airport, an IAA spokeswoman said she could not rule out further delays should the unofficial action continue.
"Tonight there was a particular problem," she said. "There could be further delays over the weekend...although it may not be as critical as tonight."
In a statement last night, Impact said "significant progress" had been achieved in the recent LRC talks, with face to face talks between it and the IAA scheduled for this Wednesday.
"Impact trade union are tonight talking with air traffic controllers and urging them to make themselves available for overtime on a voluntary basis, as has been customary practice," it said. "Impact have told air traffic controllers that this is crucial to the facilitation of talks with the IAA."
A spokeswoman for Ryanair said it expected flights to be delayed by up to one and half hours, due to a situation which was "out of our control". A Dublin Airport Authority spokeswoman advised passengers to check with their airlines before travelling.