PHOENIX - The federal government is serious about following through on its promise to crack down on employers in Arizona who break the law by hiring illegal immigrants, a top-ranking immigration official said Wednesday.

Some businesses regard the fines they could face for illegal hirings as the price of doing business, so the government will now pursue criminal charges against the most egregious violators, said Alonzo Pena, the new chief of investigations for Immigration and Customs Enforcement in Arizona.

"If you knowingly exploit this system, you are going to jail," Pena said. "We are going to go after the profits that you make. We are going to make an example."

With limited resources to crack down on the large number of illegal hirings in Arizona, federal authorities said such prosecutions will help deter other employers who might be thinking about flouting the rules.

The government also is holding classes to teach businesses about employment eligibility rules and how to spot fake documents that a prospective worker might present when applying for a job.

Employers who hire illegal immigrants are blamed for encouraging people to sneak across the border in hopes of finding better paying jobs. Many lawmakers and immigration analysts have given the federal government poor marks in cracking down on illegal hirings.

After the 2001 terror attacks, the government's employment enforcement efforts centered primarily on work sites with implications for national security - nuclear plants, military bases, airports, chemical plants.

This spring, federal officials announced a plan to intensify crackdowns on illegal hirings, including those businesses that don't have national security implications.

Crackdowns could land an especially hard blow on the Arizona economy, where an estimated one in 10 workers is an illegal immigrant.

Immigration analysts and some politicians have criticized the government for backing down in past crackdowns after businesses complained about the enforcement efforts.

Pena said the government's decision to increase the number of Border Patrol agents and put National Guard troops at the border are signs that the government is serious about confronting illegal immigration.

Cracking down on illegal hirings is a top priority, said Pena, whose office is responsible for immigration enforcement beyond the borderlands.

"We have to have this second piece - this interior enforcement," he said.

On the Net:

Immigration and Customs Enforcement: http://www.ice.gov