NEW BEDFORD -- Up to 500 workers have been arrested at a leather factory in New Bedford in what federal officials are calling one of the largest illegal immigration workplace raids in recent memory.

The company, Michael Bianco, Inc., of 89 Rodney French Blvd. is contracted to make backpacks and ammunition holders for the Pentagon that are used in Iraq.

Immigration agents from across the country were brought to the region to conduct the 8:15 a.m. raid, which involved a Coast Guard helicopter and hundreds of law enforcement personnel. The exact number of undocumented workers arrested is unclear, but officials said the number could be as high as 500.

Five company managers were arrested as well, including the owner, who was charged with "conspiring to encourage or induce illegal aliens to reside in the United States, and conspiring to hire illegal aliens," according to the U.S. Attorney's Office in Boston.

The factory and surrounding streets were blocked off to the public this afternoon as federal immigration agents continued to interview workers inside. Those determined to be in the country illegally -- and that number is expected to be upwards of 500 -- will be placed in a federal detention center in Massachusetts pending the outcome of immigration proceedings.

The crowd gathered outside the factory today included many workers' relatives, who said that the bulk of workers' arrested are women. Social advocates said they contacted all the schools and day care centers in the area to ensure children weren't abandoned.

Helena Marques, of New Bedford's Immigration Assistance Center, said many fathers may not pick up children today, fearing that they could be arrested as well. She noted that an area church would stay open all day and night to help people find their relatives and answer questions.

Immigration and Customs Enforcement spokesman Richard Rocha said that today's raid was the result of an 11-month investigation dubbed Operation United Front in which at least one federal agent posed as a factory worker.

"The message to employers is that you can’t hire people who are here illegally,” Rocha said, adding that those hired illegally "are taking jobs away from other people in New Bedford."

Company officials arrested include owner Francesco Insolia, 50, of 3 Country Club Circle, Pembroke, Mass.; payroll manager Ana Figueroa, 40, of 150 Thompson St., New Bedford; plant manager Dilia Costa, 55, of 43 Sherman St., New Bedford; and office manager Gloria Melo, 41, of 135 Sprague St., Fall River. Each is charged with conspiring to encourage or induce illegal aliens to reside in the United States.

Another company official, Luis Tores, 45, of 500 South Second St., New Bedford, was charged with the knowing transfer of fraudulent identification documents. Each was scheduled to appear in federal court today.

“It is understandable that many from around the globe would want to come to live, work and raise families here in the greatest democracy in the world. However, this must be done in compliance with U.S. immigration laws - not in violation of them,” Massachusetts U.S. Attorney Michael J. Sullivan said in a statement. “Employer accountability is essential to ensuring the integrity of the nation's immigration system and knowingly hiring illegal immigrants is a violation of law, plain and simple, and those responsible will be prosecuted.”

The U.S. Attorney's Office says that while the company required all prospective employees to produce proof of their identity and their eligibility to work, Bianco was aware that many employees obtained fraudulent Alien Registration Cards, or “green cards,” and Social Security Cards. Prosecutors said that company managers even instructed prospective employees, including the undercover federal agent, on how to obtain the fake documents.

Why would the managers hire illegal workers? The government contends that the company "intentionally seeks out illegal aliens because they are more desperate to find employment, and are thus more likely to endure severe workplace conditions," according to a statement.

Prosecutors allege that the conditions include the following: docking of pay by 15 minutes for every minute an employee is late; fining employees $20 for spending more than two minutes in the restroom and firing for a subsequent infraction; providing one roll of toilet paper per restroom stall per day, typically resulting in the absence of toilet paper after only 40 minutes each day; fining employees $20 for leaving work area before break bell sounds; and fining employees $20 for talking while working and firing for a subsequent infraction.

Michael Bianco, Inc. specializes in the manufacture of handbags and other fine leather goods, according to federal investigators who note that between 2001 and 2003, the company won a number of Department of Defense contracts worth approximately $10 million. In 2004, Bianco received another defense contract worth approximately $82 million. As a result of these defense contracts, according to the U.S. Attorney's Office, the company began to substantially increase its workforce from about 80 employees to about 525.