GREELEY, Colo. -- Members of a food workers' union are calling for congressional hearings, asking lawmakers to look into the tactics that were used during last year's immigration raids at the Swift plant in Greeley.

In a nationwide meeting Thursday in Nebraska, community members and union workers say employees at the plant had their civil rights violated.

Union workers said many who were originally detained are, in fact, legal citizens. The union said 12,000 meat packers were detained and about 1,200 were arrested.

But the union contends almost all of them were deprived of their rights, with no access to water, food, telephones or legal counsel when immigration officials raided the Swift plants across the country last December.

"I'm very frustrated because I have been a citizen here all my life. I have never been in this kind of situation, and I felt very violated because of the fact they had me in handcuffs and I didn't do anything wrong," said Swift employee Mike Graves.

In a meeting in Omaha, Neb., union workers said the tactics used by immigration officers were unacceptable. Joseph Hansen, president of the United Food and Commercial Workers International Union, said the union will start holding hearings around Nebraska and Colorado to catalog workers' experiences during raids by ICE agents.

One worker claimed they were treated worse than the animals that are sacrificed at the plants.

Outside of the meeting, protesters marched the sidewalk, supporting the raids.

"They are in there giving their sob stories about how their families are being torn apart and all this. They knew when they crossed the border illegally that if they got caught they would be deported," said one protester.

The protesters said government agents are just doing their job, enforcing the laws.

A spokesman for Immigration and Customs Enforcement said the actions taken by ICE agents and officers were fully within the law.

He said authorities had criminal search warrants, which gave them the legal authority to enter the plant, search and question every single individual.

The union said it does plan on filing a federal lawsuit against ICE for what it is calling "military tactics" that violated workers' Fourth Amendment rights against illegal search and seizure.

Meanwhile, the Brazilian company that bought the Greeley meatpacking plant from Swift is finding it slow going to hire staff for a second shift.

The Greeley Tribune said the company said it has hired some workers but is not where it wants to be. And once the workers are hired, it will take some months to get them all trained.

JBS announced last month that it would start running a second shift.

Many Colorado companies are reporting labor shortages, blaming a crackdown on illegal immigrants.