Those workers “were making impossible demands” for the company to secure green cards for them or to repay the high fees, Mr. Schnoor said. They were “taking workers away from their work and actually trying to get them to join some effort they were organizing,” he said.

Mr. Schnoor and Darrell Snyder, a manager in the shipyard, where the Indians were living in a labor camp, said they had consulted with agents from Immigration and Customs Enforcement for “guidance” on how to fire the workers, following the rules of the H-2B program.

Mr. Schnoor said the “direction” he received from an immigration enforcement agent was this: “Don’t give them any advance notice. Take them all out of the line on the way to work; get their personal belongings; get them in a van, and get their tickets, and get them to the airport, and send them back to India.”

Signal managers said they tried to carry out those instructions on March 9, 2007, putting several Indian workers into vans to take them to the airport. They were prevented from leaving the shipyard by immigrant advocates gathered at the gates.

In an internal e-mail message 10 days later, Mr. Snyder reported that another immigration official had assured him in a meeting that day that the agency would pursue any Indian workers who left their jobs, “if for no other reason than to send a message to the remaining workers that it is not in their best interests to try and ‘push’ the system.”

Carl Falstrom, an immigration lawyer in New Orleans who is not associated with the Signal case, said there were rules for employers who fired guest workers. They are required to provide return airfare to the workers’ home countries, and they are supposed to notify the visa agency, Citizenship and Immigration Services, when workers are no longer employed. But, Mr. Falstrom said, private companies cannot carry out deportations.

Saket Soni, director of the New Orleans Workers’ Center for Racial Justice, which represents some workers in the lawsuit, said the managers’ testimony showed that immigration enforcement agents had “advised the corporation on how to retaliate against workers who were organizing.”

An ICE spokesman, Brian Hale, said he could not comment on a continuing investigation. But Mr. Hale said ICE agents were generally aware that a company that fires workers in the H-2B program “is prohibited from compelling individuals to get on the plane.”