Mexico sent a diplomatic note to the U.S. government on Monday saying a plan to build hundreds of miles of fencing on their common border would damage relations.

President-elect Felipe Calderon urged U.S. officials to reconsider the plan, saying one "could stop more migrants with a kilometer of new roads and development (in Mexico) than with a wall."

In the letter to the U.S. State Department, Mexico's Foreign Relations Department said only comprehensive reform could stem the tide of illegal immigrants heading north in search of work.

CountryWatch: Mexico

"The diplomatic note explains that the construction of this barrier will hurt the relations between the two countries and that it is not the solution to strengthen security on the border," the department said.

President Vicente Fox, who leaves office Dec. 1, has spent his six-year term lobbying for a new guest worker program and an amnesty for the millions of Mexicans working illegally in the United States — proposals that have been supported by President Bush.

However, U.S. lawmakers, who face midterm elections in November, have shown a greater appetite for border security measures. On Friday the Senate approved a bill authorizing 700 miles of new fencing in border states.

Fox has called the barrier "shameful" and compared it to the Berlin Wall.

Calderon said Monday that the barrier would not deter migrants from walking across the desert or swimming over the Rio Grande in search of a better life.

"A border that unites two nations allows the free movement of labor but is closed to drugs, guns and criminals," he added. Calderon spoke in Guatemala, where he met with President Oscar Berger on his first international tour since the July presidential election.

On Friday, Foreign Secretary Luis Ernesto Derbez said he would try to persuade Bush not to sign the bill.

"We think it is a gesture that doesn't reflect the friendship between the nations of Latin America and the Caribbean and the United States," Derbez said.

Mexican President-elect Felipe Calderon has also criticized the fence plans.

An estimated 11 million Mexican citizens are in the United States, about half of them illegally.

Last year, Mexican migrants sent home more than $20 billion in remittances, the country's second leading source of foreign income after oil. In the first eight months of 2006, remittances rose by nearly 20 percent over the same period last year, according to figures released by the Mexican Central Bank on Monday.