Federal officials arrested 300 workers in a raid on the nation’s largest kosher meatpacking plant.
Some reports said the total could reach 700 arrests.
Monday’s raid on Agriprocessors by agents from U.S. Immigrations and Customs Enforcement was said to be the largest ever in Iowa, where the company is located.
Matt Dummermuth, a U.S. attorney for the northern district of Iowa, said planning for the raid began in October.
Agriprocessors has been accused in the past of mistreating its workers and improperly slaughtering its animals.
In March, the state fined the Postville company $182,000 for health and safety violations.
The U.S. Department of Agriculture has cited Agriprocessors for food safety violations.