Mexican police have arrested 42 immigration agents and other government employees accused of running a network that smuggled illegal immigrants (search) into the United States, officials said Tuesday.

The suspects, arrested in raids last week in 12 of Mexico's 31 states, allegedly smuggled Cubans, Uruguayans, Brazilians, Asians and Central Americans through the southern border and guaranteed them safe passage into the United States. It was unclear how the ring operated in the United States.

Attorney General Rafael Macedo de la Concha (search) said his office was asking U.S. law enforcement agencies for help in determining whether any Americans were involved in the ring.

Macedo de la Concha said it was the largest smuggling ring involving officials discovered to date, and that suspects face organized crime and migrant trafficking charges.

"Unfortunately, these criminal organizations operated with protection from public servants," Macedo del Concha said, noting the officials "offered information about [police] raids, illegally freed captured migrants, and allowed them to pass with falsified documents."

Those arrested included agents and ex-agents of Mexico's National Immigration Institute (search), the INI, the very agency Mexico relies on to detect illegal migrants and prevent the country from becoming staging base for migrants from other countries.

Even more chilling was the fact that seven of the 26 INI agents arrested were assigned to Mexico's Grupo Beta, a special force designed to protect immigrants.

The suspects also included six former INI agents, seven local police and three former officers. Two non-officials who were identified as smugglers were also arrested, bringing the total number of detentions to 44.

"Immigrant trafficking is a shameful, intolerable crime," Macedo de la Concha said. "But even more serious is the participation of public servants, because beside damaging people, that also hurts our institutions and principles."

Deputy Attorney General Jose Luis Santiago Vasconcelos said the traffickers charged between $2,000 and $6,000 to get immigrants into the United States. The highest price was charged for smuggling Asians.

The ring operated in the northern border states of Baja California, Chihuahua and Nuevo Leon; the southern border states of Chiapas and Quintana Roo, and the central Mexico states of Jalisco, Tabasco, Veracruz, San Luis Potosi, Mexico and Mexico City.