Tijuana, Mexico — Mexican immigration officials are preparing to ramp up inspections of U.S. citizens and other foreigners entering the country on foot, requiring those crossing from San Ysidro to show travel documents such as a U.S. passport or passport card.

The head of Mexico's National Migration Institute in Baja California, Rodulfo Figueroa, said that the new push will begin by September with the expected opening of a new building housing Mexican immigration and customs inspections stations at the Tijuana pedestrian entry. Figueroa said that the measures will be enforced gradually, and inspectors will be sensitive to the flow of people entering the country.

"We will do everything we can to make the transition as seamless as possible," Figueroa said. "People should not be panicking about this. We're not going to create a four-hour southbound wait."

The measures should not be that much of a burden on most U.S. citizens, as they are already expected to show passports or other valid travel documents when re-entering the United States.

Previous efforts by Mexico's federal government to enforce immigration inspections in Baja California have met with stiff resistance from business leaders and tourism authorities fearful that the passport requirement would discourage visitors to the state. Particularly touchy was a requirement that those visitors planning to remain in Mexico for more than seven days pay a 330-peso fee, about $21.

Last November, a pilot inspection program aimed at pedestrians crossing into Mexico at Otay Mesa was canceled after Baja California Gov. Francisco Vega de Lamadrid took up the issue with Mexico's immigration commissioner.

Figueroa said the new plan has the full support of his higher-ups. Immigration inspectors currently inspect documents of all southbound bus riders entering Tijuana from San Ysidro through the El Chaparral port of entry, and have been conducting some inspections on pedestrian crossers at the discretion of immigration inspectors, the official said.

With the opening of new building, authorities plan to create two lanes for pedestrians entering Mexico, one for Mexican citizens and the other for foreigners. "If we don't have enough agents to review everyone, we'll review everyone we can," Figueroa said. "Our intention is not to create congestion at the border. Our intention is to try different strategies to process as many people as we can within a reasonable time frame."

Similar inspections for those driving across into Mexico are also contemplated, but these "are way, way into the future," Figueroa said.