A $410 billion government spending bill that President Obama signed on March 11 barred spending on an 18-month-old pilot program that allowed a few Mexican trucks beyond a border buffer zone, according to the Associated Press.

The U.S. prohibits most Mexican trucks from driving more than about 20 miles, or 75 miles in Arizona, beyond the border. But the U.S. agreed to lift that ban after signing the 1994 NAFTA deal with Canada and Mexico.

Canadian trucks have no limits on where they can go. But limits-imposed after lawmakers voiced safety concerns-state that most Mexican trucks can't travel beyond a buffer zone along the southern border. Mexico has long called it an unfair effort to protect U.S. jobs. The previous pilot program allowed access for up to 500 Mexican trucks from 100 operators and allowed the U.S. to conduct inspections and other safety activities.

A spokeswoman for the Office of the U.S. Trade Representative said Obama has told the office to work with Congress, the Transportation and State departments and Mexican officials to come up with legislation creating "a new trucking project that will meet the legitimate concerns" of Congress and U.S. commitments under the North American Free Trade Agreement.

The Mexican government has protested the trucks ban, and prohibits U.S. trucks from driving far into Mexico.