Shop stewards representing security staff at Dublin Airport are due to meet tomorrow to discuss the possibility of strike action.
SIPTU has accused the Dublin Airport Authority of attempting to change the workers' terms and conditions without consultation and of refusing to discuss other outstanding issues.
Speaking ahead of today's talks, union spokesman Pat Ward said strike action was a real possibility.
"Feelings are running quite high within the representatives of the police and the airport search unit and certainly I would not rule out a measured response from both sections of the workforce," he said.