Ryanair passengers could face flight disruption this summer if cabin crew go through with threats to strike.
Unions in Spain, France, Portugal, Italy and Belgium have all threatened industrial action over pay.
Labour organisations including SITCPLA and USO have come together to demand an uplift, claiming they have "no other option" but to walk out if it is not given.
The move comes after Ryanair - Europe's largest budget airline - walked away from talks with USO and SITCPLA on Tuesday, Bloomberg reports.
A spokesperson for the latter union said: “We’re coordinating our actions with European counterparts.”
USO and STCPLA said in a joint statement that Ryanair lacked commitment to dialogue and accused the airline of acting in bad faith.
Negotiations on a collective agreement made “almost made no progress” due to the unions’ “unrealistic demands and refusal to meaningfully engage,” a letter from Ryanair said following the failed talks.
It is unclear when the strikes will take place, and how many flights will be impacted.
If the Spanish unions go through with their threat, then Brits travelling to holiday hotspots may well be impacted.
A spokesperson for Ryanair told The Mirror: “Ryanair has negotiated collective agreements covering 90% of our people across Europe. In recent months we have been negotiating improvements to those agreements as we work through the Covid recovery phase.
"Those negotiations are going well and we do not expect widespread disruption this summer.
"In Spain, we are pleased to have reached a collective agreement with CCOO, Spain’s largest and most representative union, delivering improvements for Spanish-based cabin crew and reinforcing Ryanair’s commitment to the welfare of its cabin crew.
"These announcements by the much smaller USO and SITCPLA unions are a distraction from their own failures to deliver agreements after three years of negotiations and we believe that any strikes they call will not be supported by our Spanish crews.”