The Spanish government Tuesday gave preliminary approval to extending a state of emergency to ensure that another air traffic controllers' strike will not paralyse airports during the Christmas season. The government had declared the state of emergency on December 4 to force the controllers to return to work after they went on a wildcat strike, leaving more than 600,000 passengers stranded over 24 hours. The measure placed the air controllers under military law and left them facing jail time unless they returned to their posts, according to dpa. The initial state of emergency was to remain in force until December 18. The cabinet extended it until January 15, Infrastructure Minister Jose Blanco said. The government's decision needs to be endorsed by parliament, which was expected to approve it on Thursday. The unofficial air controllers' strike was not an isolated event, but followed a string of "threats and blackmail," Blanco said earlier in the day.