MEXICO CITY, Sept 2 (Reuters) - Mexican President Felipe Calderon accused the United States on Sunday of stepping up persecution and abuse of undocumented Mexican workers with a crackdown on illegal immigrants.

The Bush administration is increasing scrutiny and imposing heftier fines on U.S. businesses that employ illegal workers, after deporting a record number of illegal immigrants in 2006.

"I want to express again an energetic protest at the unilateral measures taken by the U.S. Congress and government which exacerbate the persecution and abusive treatment of undocumented Mexican workers," Calderon said in his state of the union speech.

Mexico was deeply disappointed at the U.S. Congress' failure to pass a comprehensive overhaul of immigration laws in June despite heavy lobbying by the Bush administration. It is also upset at the United States for building a security fence on parts of the border to keep illegal immigrants out.

"The Mexican government will continue to insist firmly ... on the need for an integral immigration reform and the categorical rejection of the building of a wall on our common border," Calderon said to raucous applause.

U.S. employers who ignore immigration laws will face an increased likelihood of criminal charges and 25 percent higher penalties.

The new enforcement effort, announced in August, could create headaches for U.S. farms, restaurants, construction companies and other businesses that rely on low-skilled immigrant workers.

Some 12 million illegal immigrants live in the shadows in the United States. Last year, Immigration and Customs Enforcement agents deported 183,431 people amid stepped up raids on workplaces and homes nationwide.

Calderon, a conservative, last week met Elvira Arellano, 32, an undocumented Mexican who became famous among pro-immigration activists for defying deportation orders and claiming sanctuary in a Chicago church for a year.

In a meeting in his Los Pinos residence, he promised to help Arellano obtain a visa for the United States.

Calderon, who took office last December, had to give his annual state of the nation speech to ministers, business leaders and other dignitaries on Sunday after canceling plans to deliver it in Congress on Saturday because of protests by leftist lawmakers.

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