Ryanair has said it does not expect widespread disruption this summer, following a threat of industrial action by some staff in Spain.
Spanish cabin staff said today that they will go on strike for six days in late June and early July.
The staff will walk out on June 24, 25, 26 and 30 and on July 1 and 2, as they are unhappy with working conditions and pay, USO union said.
"We have to resume mobilisation so that the reality of our situation is known and Ryanair is forced to abide by basic labour laws," said Lidia Arasanz, the general secretary of USO's Ryanair section, in a statement.
Staff of Dublin-based Ryanair, the largest airline in Europe in terms of passenger numbers, have walked out in other European countries such as Belgium and Italy.
However, the airline said in a statement that it has already negotiated collective agreements that cover 90% of its staff across Europe.
"In recent months we have been negotiating improvements to those agreements as we work through the Covid recovery phase," it said.
"Those negotiations are going well and we do not expect widespread disruption this summer."
The airline said it had also reached agreement with the Spanish CCOO union.
"Recent 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 their strike calls will not be supported by our Spanish crews," the airline added.
With most Covid-related travel restrictions lifted in many countries in recent months, demand for summer travel has bounced back, leaving airlines and airport operators struggling to hire staff fast enough to handle the flow of passengers and offer them attractive working conditions.