MEXICO CITY, Mexico: The president of Mexico Vicente Fox has likened a United States plan to build a 700-mile fence along their border to the Berlin Wall describing it as "shameful".

He said the proposal was a "very bad signal" from a nation of immigrants.

Last week, the US House of Representatives passed an immigration bill backing the building of the fence. The controversial bill - which the US Senate is due to debate in February - also includes the use of troops and police to halt migrants, and tighter employment controls.

About 10m Mexicans are believed to live in the US, some 4m of them illegally. More than a million are arrested every year as they try to enter the US to seek work.

"This wall is shameful," Fox said. "It's not possible that in the 21st Century we're building walls between two nations that are neighbors, between two nations that are brothers."

"When we look at their roots, the immense majority of [Americans] are migrants, migrants that have arrived from all over the world," he added.

The US has already built a wall between San Diego and Tijuana, and now plans to fence off other parts of the border in California, Arizona, New Mexico and Texas.