Talks between Ryanair and its main Irish pilot union over the restoration of Covid-19 pay cuts have been "exhausted", the Forsa union said on Twitter.
It added that it had asked the Workplace Relations Commission to mediate.
Ryanair said in a statement that over 85% of its pilots were now covered by deals including "long-term pay agreements including accelerated pay restoration and ongoing pay increases" and it blamed Forsa for the impasse.
"Ryanair has no difficulty with third party mediation but that cannot be a substitute for genuine and meaningful negotiations between the company and the union," the statement said.
Ryanair in July said it had agreed on terms to restore pay cuts with all pilot unions other than in Ireland and Belgium.
The airline saw minor disruption this summer due to cabin crew strikes.
