GREELEY, Colo. -- Agents with the Immigration and Customs Enforcement returned to at least one Swift & Co. meatpacking plant Tuesday with arrest warrants for people suspected of identity theft in an operation that garnered union support.

Officials with the United Food and Commercial Workers Union said agents did not appear to use the "same level of intimidation and overkill" as raids in December that resulted in more than 1,200 immigrant workers being arrested at plants in six cities.

"To the extent this is the case, the UFCW supports law enforcement efforts that abide by the law and respect the rights of workers," the Washington-based union said in a statement.

ICE spokeswoman Virginia Kice said two people were arrested on warrants unrelated to the agency's identity theft investigation. While ICE agents were at the plant, they discovered one person with a traffic warrant from the Greeley Police Department and another with a prior criminal offense that made the person deportable, Kice said.

However, spokesman Carl Rusnok called the arrests "targeted," and said warrants were executed on people identified as using stolen identities reported to the Federal Trade Commission. Speaking from Dallas, Rusnock said Tuesday's actions were part of an ongoing look into undocumented immigrants at the plants.

Dave Minshall, spokesman for Local No. 7, said agents had at least 40 arrest warrants for suspects in Greeley; Cactus, Texas; Marshalltown, Iowa; and Worthington, Minn.

Four people were questioned at the Greeley plant, Minshall said.

Rusnok declined Wednesday to confirm any arrests in Greeley. He said the agency would release details of the "worksite enforcement operation" later.

In the December raids, no charges were filed against Swift, a Greeley, Colo., which bills itself as the world's second-largest beef and pork processor.