Travellers to Spain have been warned to expect a summer of disruption as air traffic controllers stage a series of strikes over working conditions, despite some earning up to €1m per annum.

The Spanish government has warned that it may bring in military air traffic controllers to cover for striking staff that have already brought flight disruptions to Southern Europe this week.

Transport Minister Jose Blanco said: “In exceptional situations we will employ aerial military controllers to guarantee aviation traffic in our country. We are obliged to take alternative measures.”

Spain’s air traffic controllers have been locked in a bitter industrial dispute with the Spanish government over pay and working conditions. The strike in Spain follows similar action in France which saw 20 per cent of flights from Paris’ Roissy airport cancelled.

Almost half the controller’s at Barcelona’s El Prat airport scheduled to report for work this week called in sick, causing widespread delays to airports on the east coast of Spain and the Balearics.

This followed several days of similar action leading to serious delays and numerous cancellations on one of the busiest weekends of the summer season.

Minister Jose Blanco blamed the latest absenteeism on an “orchestrated campaign” and called for a full investigation into the fact that so many air traffic controllers had “fallen ill overnight”.

Delays were expected to continue throughout the summer on flights to holiday islands of Majorca and Ibiza, as well as Valencia and Alicante which service the Costa Blanca. A small number of flights were cancelled but delays averaged half an hour.

In February the Spanish government ended what it described as the “incomprehensible privileges” of air traffic controllers, including their high rates of pay and benefits.

Controllers in Spain earn a basic salary of €200,000 and can take home up to €1 million with overtime.