The Spanish Government may deploy the military to replace the increasing number of Barcelona air traffic controllers on sick leave in an effort to stop flight delays at its airports.
It is suspected that air traffic control staff absences, which have tripled in the last few months, are a result of an undercover strike.
Spain's Transport Minister José Blanco said that in exceptional situations the government could employ aerial military controllers to guarantee aviation traffic in the country, according to AFP.
Blanco said that the level of staff on sick leave in Barcelona's control centre fell slightly to 32% on 20 July from 36% on 19 July.
Secretary of State for Transport Concepcion Gutierrez said training will be given to military air controllers before the end of July.
An investigation will be launched to find out the exact reason behind the sick leave taken in the past few days by air traffic control staff at Barcelona's control centre.
The staff shortages have affected airports in Catalonia and Balearic Islands.