Federal agents conducted a raid Tuesday morning at Sparboe Farms, a major Minnesota egg producer, executing a search warrant on the company's offices and arresting 10 people on immigration-related charges.

Authorities said the operation by immigration and Homeland Security agents was part of a "larger criminal investigation,'' but declined to give further details.

The morning-long raid at Sparboe's operation in Litchfield, Minn., included a Homeland Security helicopter and assistance from the State Patrol.

Two of the individuals arrested were later released for "humanitarian reasons,'' officials said, but eight were held on administrative charges, a tool that federal officials often use to detain people suspected of immigration violations.

Shawn Neudauer, regional spokesman for U.S. Immigration and Customs Enforcement (ICE), declined to reveal the reason for the raid, but said that what brought agents to Sparboe was separate from what led to the arrests.

In a statement issued late Tuesday, the company said it knows of no food safety or quality concerns at issue, and that it works hard to comply with federal immigration law.

"Sparboe Farms invests significant resources in immigration-related compliance,'' the statement said. "We conduct documentation verification to assess the eligibility of all employees to work in the United States. Employees involved in the hiring process receive ongoing training. In addition to ongoing training, self-audits of personnel records have been conducted.''

Neudauer said he knew of no previous immigration investigations or citations at the company.

Large-scale immigration raids at Midwestern meat and poultry operations became common in the mid-2000s, with federal agents swarming industrial compounds and taking suspected illegal workers away by the busload.

In the last four years, however, the Obama administration has instructed ICE to direct its efforts away from minor immigration infractions and toward violations involving serious felonies, such as human trafficking and drug smuggling, and at employers suspected of systematically hiring undocumented workers or abetting immigration violations.

Sparboe, the nation's fifth-largest egg producer, sells to retail, wholesale and food-service customers. It is based in Litchfield, about 65 miles west of Minneapolis.

Sparboe took a public relations hit in November 2011 when an animal rights group released a video of conditions in hen housing owned by the company. Taken in Minnesota, Iowa and Colorado, the video portrayed crowded cages common in the industry, but also showed one worker swinging a chicken by a rope or chain and another stuffing a hen into a co-worker's pants pocket.

After the video came out, Sparboe was dropped as a supplier by McDonald's, Target Corp., Lund's, Byerly's and other major grocery chains.

The company said that after learning of the video, it launched a "comprehensive internal investigation," and brought in an expert from Iowa State University to conduct a welfare audit.

And in 2010, Sparboe was one of a group of companies targeted by a coalition of restaurants and food processors who sued the nation's big egg producers for alleged price-fixing. Sparboe settled and agreed to cooperate with the plaintiffs.

Staff writer Paul McEnroe and the Associated Press contributed to this report. Paul Walsh 612-673-4482