A union representing the flight controllers has issued a veiled threat to "covertly strike" in the run up to Easter in an ongoing battle over employment contracts.
Jose Blanco, the development minister who oversees Spain's airports has vowed to slash the salaries of air traffic controllers in a bid to reduce costs at Spain's loss-making airports.
It was revealed that some controllers are earning up to £800,000 after adding overtime pay to the basic salary of £175,000.
The data was revealed against the wishes of the air traffic controllers' unions and provoked outrage across Spain, where the average salary is £16,000, according to government figures.
Mr Blanco said he wanted to see a 40 per cent reduction in the take home pay of air traffic controllers after it emerged Spain's 48 state-run airports had incurred a loss last year of £260 million.
"I have taken the decision to take the bull by the horns and end the privileges of these controllers," he told the Spanish parliament.
Spain's state airport operator is currently negotiating with the air traffic controllers over a new contract which will freeze wages and limit overtime when the current agreement runs out at the end of March.
A public statement made by the controllers' union rejected the cuts and warned that it would lead to undercover industrial action during the Easter week.
"You will have to put up once again with the suspicion of a covert strike," it said.
The air traffic controllers were accused of deliberately disrupting flights over the Christmas period when they staged a period of work-to-rule.