Ryanair cabin crew in four countries are set to strike later this month.
Unions said they are taking the action after Ryanair refused to meet a series of demands about employment conditions before a deadline.
In a statement, the unions involved said: "Regretfully, Ryanair chose to continue to ignore its workforce.
"[They] gave these unions no other choice but to call for a national 24 hours strike action in Portugal, Italy, Spain and Belgium for the 25th of July and in Portugal, Spain and Belgium for the 26th of July."
A separate strike by Dublin-based pilots is still set to go ahead in a week's time, on July 12th.
Ryanair has called on the Irish Airline Pilots Association (IALPA) and its parent union Fórsa to call of the action.
Ryanair calls on FORSA to call off strike and meet: pic.twitter.com/aLWPY73Fwi
— Ryanair (@Ryanair) July 4, 2018
However, in a letter to Ryanair today, IALPA said: "At every stage we have consulted our members and they took the decision to proceed with the ballot and serve notice because they have seen no evidence whatsoever on the part of Ryanair management to engage in meaningful negotiations with a view to reaching agreement on the issues they have presented to the company.
"We have consistently suggested a neutral venue which we will pay for and it is beyond anyone’s understanding why you will not simply agree to this."
Pilots here are demanding the introduction of a seniority system at the airline.