Unions representing Ryanair cabin crew in Spain on Wednesday announced plans to hold 10 days of strikes in September unless the Irish airline changes its plans to close several bases in the country.
Ryanair staff unions in Britain, Ireland and Portugal have already announced plans to strike in the coming weeks over pay and conditions.
Ryanair pilots in Spain are also due to vote on possible industrial action.
The low-cost carrier , Europe's largest, managed to quell a series of industrial disputes last year by reaching recognition agreements with a number of unions in Europe and deals on pay and conditions with some.
But it has yet to move beyond recognition agreements with others and management angered staff two weeks ago by informing them it had 900 more pilots and crew than needed due to delays in the delivery of the grounded Boeing 737 MAX.
The SITCPLA and USO workers' unions said the threat of strike action was aimed at preventing the planned closure of bases at Gran Canaria, Tenerife South and Girona airports.
In a statement the unions said they planned to formally lodge notice of strikes on September 1, 2, 6, 8, 13, 15, 20, 22, 27 and 28, unless Ryanair made concessions in the coming days.
SITCPLA spokesman Manuel Lodeiro said in a statement the unions were open to mediation by Spanish labour agency SIMA but added "we doubt very much the willingness of Ryanair to reach an agreement."
Ryanair did not immediately respond to a request for comment.
