Mexican President Vicente Fox stepped up his attacks on the United States plan to build a fence along its southern border on Sunday, saying it was a "shameful" initiative for a democracy.

Fox said barriers between nations belonged to the last century and had been torn down by popular uprisings, referring to the fall of the Berlin Wall in 1989.

"This wall is shameful," Fox said at an event for migrants in his home state of Guanajuato.

On Friday, the U.S. House of Representatives voted 239-182 in favor of an immigration enforcement bill, which includes a proposal to build 700 miles of fence through parts of California, Arizona, New Mexico and Texas.

Under the bill, soldiers and police would help stop people sneaking across, and employers would have to check the legal status of their workers.

Fox said the measures were hypocritical for a country made up of immigrants.

"When we look at their roots, the immense majority are migrants, migrants that have arrived from all over the world," he said.

Since he came into power in 2000, Fox has lobbied the U.S. government to allow more Mexicans to work legally in the United States.

President Bush has proposed a new guest worker program with three-year work visas, but lawmakers refused to include the program in the immigration bill passed Friday.

U.S. authorities estimate there are about 11 million undocumented migrants in the United States, about half of them Mexican.