Up to 1,200 jobs could be lost at Aer Lingus if the airline is sold to IAG, according to the IMPACT trade union.
The union said the group has a history of cutting jobs after takeovers.
The Oireachtas transport committee is holding an emergency meeting this afternoon to discuss the potential impact of the airline being sold.
IMPACT's Matt Staunton says there were huge job losses when IAG was formed in the first place.