Earlier this month, the ground crew for International Airlines Group’s Iberia airline called strikes on Aug. 24-25 and then on Aug. 30-31. Iberia cancelled six flights for this coming Saturday to or from Barcelona and another six for Sunday, an airline spokesperson said.

Combining both Vueling, which is also owned by IAG, and Iberia, 124 flights have been cancelled in Barcelona for this coming weekend.

Barcelona-based Vueling, which usually has around 600 to 700 weekend flights from Spain's second-largest airport, said it had been re-booking travellers on other flights. It warned that other airlines' flights would also be affected.

El Prat is Spain's second-largest airport after Madrid's Barajas. Its traffic grows in summer during the peak tourist season.

Spanish trade union UGT has called on Iberia ground staff in Madrid to also strike on Aug. 30 and 31. The union's main demands are more full-time contracts, training, and the use of new vehicles.

(Reporting by Ashifa Kassam and Joan Faus; writing by Andrei Khalip; editing by Larry King)