Dos Bocas and Coatzacoalcos, the two other Mexican crude ports in the Gulf where Hurricane Gustav is bearing down on the U.S. Gulf coast and has forced tens of thousands of people to flee their homes, were still open, the ministry said.
Gustav, although moving west-northwest and away from the southern part of the Gulf of Mexico, was causing waves of six to eight feet (1.8-2.4 meters) near Cayo Arcas, the ministry said.
Together the three ports ship about 80 percent of Mexico's crude exports, the bulk of which goes to U.S. refineries.
Mexico is the world's No. 10 exporter of crude oil, according to the U.S. Energy Information Administration (EIA) and a major U.S. supplier.
State oil monopoly Pemex says its export volumes are rarely hurt by temporary port closures, as it reschedules delayed shipments once the weather clears.