Thousands of people marched in Mexico City on Sunday to protest President-elect Andres Manuel Lopez Obrador's plans to cancel a new US$13 billion airport for the capital.

Marchers dismissed the referendum that led to the cancellation as unconstitutional and compared Lopez Obrador to Venezuela's socialist president, Nicolas Maduro.

Last month, 70 percent of participants voted against continuing the project, which Lopez Obrador has criticized as too costly. Just over 1 million people voted.

Critics quickly dismissed Sunday's demonstration as the "Fifi march" on social media. Lopez Obrador has taken to calling frivolous things "fifi."

Many of the marchers appeared to be of a social class seldom seen marching in the capital's streets.

The new airport is already about one-third completed.