Mexico Restricts Work on Chrysler Plant : NAFTA: Move is seen as an attempt to counter environmental concerns of critics.

MEXICO CITY — In an apparent attempt to show they are serious about enforcing environmental regulations, Mexican authorities have halted some construction at the site of Chrysler’s Ram pickup truck plant, scheduled to open south of Saltillo early next year.

Officials in charge of environmental protection said Wednesday that the government took the action because the company failed to conduct environmental impact studies or obtain building permits.

“The studies are indispensable to protecting the environment and to avoiding possible damages that could be irreparable,” a statement from the attorney general for environmental protection said.

The action against Chrysler appears to be designed to counter concerns by critics of the North American Free Trade Agreement that U.S. and Canadian manufacturers will flee to Mexico to escape pollution controls in their home countries.

The government has made similar announcements in the past, and critics noted that previous work stoppages have been temporary and that punishments for violations have not been severe.

The multimillion-dollar Chrysler project includes an electric power substation and a natural gas pipeline that would cross the mid-sized city of Saltillo. The assembly plant, which would have a capacity of 110,000 trucks a year, is 200 miles southwest of Laredo, Tex. It is scheduled to produce pickups mainly for export to the United States and Canada.

Chrysler de Mexico spokesman Leopoldo Silva said construction of the factory continues, but he confirmed that work on the substation and pipeline have been halted. He said a paperwork mix-up was responsible.

“As soon as the documentation is checked and verified, we should be able to open immediately,” he said. “We have done the studies.”

Mexican environmental law calls for studies of any construction that could cause “ecological disequilibriums” and specifically requires reports to federal authorities on natural gas pipelines, electric transmission installations and automotive plants.

NAFTA will gradually eliminate barriers to trade among the United States, Mexico and Canada. It was strongly opposed by U.S. labor unions, including the United Auto Workers.

As NAFTA opponents argued that U.S. companies would use the agreement to move production to Mexico to take advantage of lax environmental controls, Mexico strengthened its anti-pollution laws and beefed up enforcement.

“There has been a lot of criticism lately about Mexico’s follow-up to NAFTA,” said Geoff Land, border coordinator for the Border Ecology Project in Bisbee, Ariz. “If this means that Mexico is taking a closer look at companies setting up there that could have a negative environmental impact, that’s good.”

However, he also noted that “every few weeks or months, an incident like this brings up the question of whether Mexico is finally getting serious about environmental enforcement.”