Thousands of teachers blocked road access to Mexico City's international airport on Friday, snarling traffic in the megalopolis to protest education reform.

The striking educators descended on the capital this week from across the country, staging sit-ins at the chamber of deputies and senate that forced lawmakers to move their debates in a convention center.

Airport director general Alfonso Sarabia said travelers were forced to take the metro to reach the two terminals after the teachers blocked car access.

"The airport is still operating, flights are landing and taking off, but many passengers are arriving late," he told Radio Formula.

Jesus Rodriguez Almeida, the city's public security secretary, said 1,700 police officers were deployed to guard the terminals, warning that operations there would only be interrupted "over my dead body."

Mexico City Mayor Miguel Angel Mancera said Thursday that his government respects the right to protest and that his priority was to prevent clashes "at all cost."

More than 70,000 teachers went on strike in southern Mexico, leaving more than one million children without classes at the start of the school year this week.