The 24-hour strike by Spanish air traffic controllers has cost the tourist and airline sectors hundreds of millions of euros and the political cost for an already unpopular government could be much higher.

A walk-out by the controllers on Friday paralyzed airports and stranded hundreds of thousands of travelers after the cabinet approved new rules regulating their hours and agreed a partial sell-off of airport authority AENA.

There were no official estimates, but newspapers said the strike may have cost the tourism industry as much as 350 million euros and airlines more than 100 million euros ($134 million).

It's too early to put a figure on the cost of the disruption, an AENA spokesman said on Sunday.

Prime Minister Jose Luis Rodriguez Zapatero declared the first state of emergency since General Francisco Franco's military rule ended in 1975 to end the unofficial action.

But images of soldiers taking over control towers will be an embarrassment to Zapatero, only days after he announced plans to raise around 9 billion euros by selling 49 percent of AENA.

Several controllers said they were herded back to work at gun point by the police and threatened with imprisonment if they didn't return to work. Spain's Deputy Prime Minister Alfredo Perez Rubalcaba denied that guns were drawn.

Can you imagine a member of the civil guard or a soldier walking in with a gun? It's simply unthinkable, Rubalcaba said during a radio interview.

Zapatero has been absent during the crisis, leaving all the explaining to Rubalcaba who promised there would be no more strikes over the Christmas period. During a 15-day state of emergency, the controllers will work under military rule.

Many families save all year for this long weekend...It's been very damaging for the hotels, for businesses and for the country's image. And somebody must take responsibility and take measures so it doesn't happen again, Rubalcaba said.

The world has to understand this will not happen again. Very drastic measures must be taken and we'll do everything that can be done, he added.

The government's tough response was widely applauded in Spanish newspapers. The controllers are an easy target, earning around 10 times the average family's wage, while Spain suffers the highest levels of unemployment in the European Union.

While even the political opposition were reluctant to criticize the Socialists for how they dealt with the strike, it will do little to change the perception of a weak government only ready to act when its back is against the wall.

While the markets gave Spain some breathing space last week, tax hikes and spending cuts and the reform pledges, have shredded popular support for the Socialists. The latest opinion poll showed they had dropped to their lowest point at any time in the country's modern democratic era.

(Reporting by Paul Day; editing by Alexander Smith)