Ryanair Holdings Plc’s Spanish cabin crew unions have announced a strike in late June and early July after pay talks fell apart.

Workers are set to strike on June 24, 25, 26 and 30, as well as on July 1 and 2, officials for the main Spanish crew unions USO and SITCPLA said in a press conference in Madrid Monday.

The two workers’ organizations are coordinating with five more unions in Belgium, France, Italy and Portugal to organize continent-wide protests if Europe’s largest low-cost carrier refuses to negotiate. Walkouts may threaten Ryanair’s recovery from the coronavirus pandemic during the summer’s high season, when travel demand is expected to reach levels similar to 2019.

Ryanair traded as much as 3.9% lower in Dublin Monday. The shares are down almost 19% this year.

Unions estimate the carrier has around 1,400 crew based in Spain. The company hasn’t implemented any collective agreement in Europe, they said.

The strike will also add pressure on airports already strained by workforce shortages and supply chain issues that have recently generated long queues at Europe’s main hubs and forced carriers to slash scheduled flights.

Ryanair earlier this month called off talks in Spain after the unions threatened a walkout, according to a letter from airline director Darrell Hughes seen by Bloomberg News. Talks on a collective agreement made “almost no progress” due to the unions’ “unrealistic demands and refusal to meaningfully engage,” the carrier said.