Suspected illegal immigrants exit the federal courthouse in Hattiesburg, Miss., to leave in a U.S. Marshal's van to a overnight holding facility, 26 Aug 2008

U.S. immigration agents have arrested nearly 600 people at a plant in the southern state of Mississippi in the single largest workplace enforcement raid in the nation's history.

Officials with the U.S. Immigration and Customs Enforcement (ICE) say agents arrested illegal immigrants, including suspects from Peru, Mexico, El Salvador, Guatemala, Panama, Honduras, Brazil and Germany.

The raid took place Monday at a Howard Industries plant, a facility that manufactures electronic transformers, in Laurel.

Some 475 were transferred to an Immigration and Customs Enforcement facility in Jena, in neighboring Louisiana.  At least 100 others, including caregivers and juveniles, were released for what authorities described as humanitarian reasons.

Immigration officials say the raid is part of an ongoing nationwide effort to shut down places of employment that hire illegal immigrants.

An estimated 12 million people are living in the United States illegally.

Immigration has been a divisive issue in the U.S. presidential campaign.  Both Republican John McCain and Democrat Barack Obama are actively courting Latino voters, who are expected to play a pivotal role in the November election.

Several battleground states have significant Latino populations, including Florida, Colorado, Nevada and New Mexico.