There will be nine days of strikes by EasyJet cabin crew in Spain in July.
The news of the planned strike by the Spanish USO union came a day after easyJet said it would be cutting 11,000 flights from its summer schedule in response to caps on flights at its bases in London and Amsterdam.
The union wants cabin staff to get a 40% pay rise. Hundreds of crew stop work at easyJet bases in Barcelona, Mlaga and Palma if the strikes go on for 72 hours.
An easyJet spokesman said: "We are extremely disappointed with this action as we have made considerable progress towards a new collective labor agreement and so would like to continue a constructive dialogue with them."
If the industrial action goes ahead, there could be some disruption to our flying programme to and from Mlaga, Palma and Barcelona, but at this stage, easyJet plans to operate its full schedule and we would like to assure customers that we will do everything we can to minimize any impact
The union said it was willing to talk. The USO members voted to go on strike for two days in the coming weeks.
Passengers should expect more disruption through the peak season, because of the shortage of airport staff, according to the chief executive of the airline.
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He told Sky News that there will be a problem at airports throughout the summer It will be better during the week.
EasyJet said it was starting to tell customers whose flights were affected by the reduction in its schedules, and that most would be rebooking on an alternative departure within a day. Most customers will be informed of any changes this week, a spokesman said.
The airline said it was considering buying 56 A320neo family planes from the manufacturer. The new planes will have more seats and use less fuel, and the airline has paid a lower price than expected.