PARIS (AP) -- Mexico's foreign secretary says his country may take a dispute over U.S. plans to build a border fence -- to the United Nations.

Luis Ernesto Derbez told reporters in Paris that a legal investigation is under way to determine whether Mexico has a case.

The Mexican government last week sent a diplomatic note to Washington criticizing the plan for 700 miles of new fencing along the U.S. border.

President-elect Felipe Calderon also denounced the plan, but says it's a bilateral issue that should not be put before the international community.

Illegal immigration and homeland security have drawn increased scrutiny in America.