MADRID (AP) Spain's government halted an air traffic control strike on Saturday by imposing an emergency decree to threaten the disgruntled employees with prison terms under military law. Flights resumed, but hundreds of thousands of travellers remained stranded at airports.

By Saturday evening the decree, which had never been used before, prompted 283 of the 295 controllers scheduled to report for duty to do so, Spain's civil aviation agency AENA said, and flights were resuming at an increasing pace at airports packed with bewildered travellers.

Spanish air space reopened after being closed with the start of the wildcat strike on Friday evening over a work scheduling dispute, but the government warned that it could be up to two days before airports return fully to normal at one of Europe's top tourism destinations.

All over the country, people marooned at airports at the start of a long holiday weekend told stories of being herded around like cattle in search of information, sleeping on chairs or floors, or resting on check-in weighing scales or propped up against their luggage.

“It's total chaos,” said Spaniard Rocio Garcia, who had hoped to spend the weekend in Paris. “There are two people attending a line of some 500 people.”

AENA said an estimated 600,000 people missed flights Friday or Saturday because of the strike.

Prime Minister Jose Luis Rodriguez Zapatero placed the country's 2,000-odd air traffic controllers under military authority in a ‘state of alarm' order, meaning strikers who refused to resume guiding aircraft in and out of airports faced the threat of jail terms under the military penal code.

Zapatero acted under a constitutional clause which had never been used before and also is reserved for national emergencies such as earthquakes or other breakdowns in essential public services.

Deputy Prime Minister Alfredo Perez Rubalcaba said on Saturday evening that AENA will investigate all air traffic controllers who failed to show up for work over the past 24 hours without due justification, and a prosecutor also is probing if they can be punished. Travellers also are filing complaints, he said.

“These are very serious events, and it is clear that accountability will be demanded,” he told a news conference.

“There will certainly be consequences for those who in an irresponsible, inexplicable and very damaging way abandoned their posts at the control towers,” Rubalcaba said.

He said the government will never allow another air traffic controllers strike to take place, but declined to explain what legal mechanisms the government would employ.

Scenes of chaos abounded.

At Barajas Airport in Madrid, Jason Bridger, 40, of Brighton, England, said: “We have been told that the airspace is open, but these guys won't open the security.”

“So the airspace is open but they won't open the airport. Loco!,” Bridger told AP Television News.

Marcos Salt, a 50-year-old from Buenos Aires, said he was in Spain en route to Vienna. “Nobody can tell me how I am going to get to Vienna or get back to Buenos Aires. They can't get you a hotel because they are all full. So we are here forgotten by God!”

The strike was yet another headache for Zapatero as he tries to pull his country out of recession and fighting off suggestions that Spain's debt load will put it next in line for a bailout, after Greece and now Ireland.

The strong-arm tactic was almost certainly a bitter pill to swallow for a man who takes pride in his Socialist ideology and always tries to curry favour with unions. It recalled a similar wildcat strike in the United States in 1981, although Zapatero stopped short of firing air traffic controllers and breaking their union, as then US President Ronald Reagan did.

Blanca Uriarte, an air traffic controller in Palma on the Mediterranean island of Mallorca, practically cried as she told reporters outside the airport what happened in the air traffic control tower on Saturday.

“The Civil Guard and the Air Force came in with pistols and forced us in this state, and I am one of the ones in best shape to sit there and guide airplanes. That is what the government did,” she told reporters. “In this state of anxiety, it is impossible to guide planes.”

The strike also was an echo of the painful austerity saga hitting much of Europe Greeks strike regularly over austerity measures imposed as part of the country's massive debt bailout and the French have taken to the streets en masse to protest a law that raised the retirement age to save the country's money-losing pension system.

In the case of the Spanish air traffic controllers, a money-saving reform enacted earlier this year slashed their salaries by about half by reducing the overtime hours they can work, which are paid at triple the normal rate.

The controllers and the government have been locked in a dispute for months over working conditions, benefits and other issues, and there has been much bad blood.

Government officials had said openly it was outrageous for some controllers to make nearly half a million euros ($660,000) a year at a time of crisis, with Spain's unemployment rate at nearly 20 percent, many people's jobless benefits running out and the average yearly salary at about €20,000 ($26,500). Even with the lower salary, the controllers make an average of ten times that figure.

The final straw seems to have been a decree approved by the Spanish Cabinet on Friday under which controllers who miss work shifts because of illness or certain other reasons must make up the lost hours and can be subject to medical checkups immediately if they call in sick.

Development Minister Jose Blanco said on Saturday that air traffic controllers have been counting hours spent at union meetings, for instance, as hours spent on the job and the decree passed on Friday ended this practice.

“It was a matter of clarifying what an hour of work is. That should not bother anyone,” he told Spanish television.

The timing of the strike was awful, and each side blamed the other for the ensuing mess. This is usually one of the busiest travel weekends of the year in Spain because Monday and Wednesday of next week are holidays, and many people planned to take Tuesday off as well, making for a mini-vacation.

The air traffic controllers union USCA and the conservative opposition Popular Party blasted the government for passing the decree right before the long travel holiday, knowing it was certain to inflame tempers. The government responded by saying it was the controllers who are to blame by choosing Friday to do their walkout.

“This has been a very hard blow to the international image of Spain. The controllers have provoked an absolutely terrible situation,” said deputy Tourism Minister Joan Mesquida.

Mesquida said it was too early to calculate how much all the missed flights and other reservations will cost the travel industry.