Mexico City ? The Mexican government, angered by a U.S. proposal to extend a wall along the border to keep out migrants, pledged Tuesday to block the plan and organize an international campaign against it.

Facing a growing tide of anti-immigrant sentiment north of the border, the Mexican government has taken out ads urging Mexican workers to denounce rights violations in the United States. It also is hiring an American public relations firm to improve its image and counter growing U.S. concerns about immigration.

Mexican President Vicente Fox denounced the U.S. measures, passed by the House of Representatives on Friday, as “shameful” and his foreign secretary, Luis Ernesto Derbez, echoed his complaints on Tuesday.

“Mexico is not going to bear, it is not going to permit, and it will not allow a stupid thing like this wall,” Derbez said. “What has to be done is to raise a storm of criticism, as is already happening, against this.”

Some stretches of the U.S.-Mexico border are already marked by fences, but in some heavily-trafficked sections walls have already been erected by the United States, often using 10-foot-high sections of military surplus steel. Those sections, which typically run several miles, can be found in southern Arizona and California.

It’s hard to underestimate the ill-feeling the proposal has generated in Mexico, where editorial pages are dominated by cartoons of Uncle Sam putting up walls bearing anti-Mexican messages.

The mistaken belief that the proposals are a done deal – they must still be submitted to the Senate – have caused “just complete fear and shock” among some activists and immigrants, said Jennifer Allen of the Tucson, Ariz.-based Red de Accion Fronteriza.

The House bill, passed on a 239-182 vote, includes a proposal to build 700 miles of additional fence through parts of California, Arizona, New Mexico and Texas. It would also enlist military and local law enforcement to help stop illegal entrants and require employers to verify the legal status of their workers.