DES MOINES (AP) – Labor officials said Tuesday that they had uncovered dozens of child labor violations at the nation’s biggest supplier of kosher meat, located in Postville.

The Iowa Labor Commissioner’s Office said an investigation, which spanned several months, uncovered 57 cases of child labor law violations at the Agriprocessors kosher meatpacking plant in Postville, where nearly 400 workers were arrested this spring in the largest immigration enforcement operation in U.S. history.

The types of violations included minors working in prohibited occupations, exceeding allowable hours for youth to work, failure to obtain work permits, exposure to hazardous chemicals and working with prohibited tools. Under Iowa law, it is illegal for children under the age of 18 to work in meatpacking plants.

“The investigation brings to light egregious violations of virtually every aspect of Iowa’s child labor laws,” Dave Neil, Iowa Labor Commissioner, said in a statement. “It is my recommendation that the attorney general’s office prosecute these violations to the fullest extent of the law.”

The child labor violations would normally be turned over to the county attorney’s office, but in this case will most likely be handed over the Iowa attorney general at the county’s request, labor officials said.

They added that they are still investigating possible wage violations at the plant.

Juda Engelmayer, an Agriprocessors spokesman, declined immediate comment on the labor officials’ announcement.

Agents arrested 389 workers in a May 12 raid at the Agriprocessors plant. That made it the largest immigration enforcement operation in U.S. history.

Trials were quickly held about 70 miles away at a fairgrounds in Waterloo, where most of the arrested workers pleaded guilty within a week. They are serving sentences in federal prisons outside Iowa before being deported.

Allegations of child labor violations were included in an initial affidavit and a search warrant that led to the immigration raid at Agriprocessors.

However, Kerry Koonce, a spokeswoman for Iowa Workforce Development, said Iowa’s child labor investigation into Agriprocessors began before the federal immigration raid in May.

She said the number of child labor violations announced on Tuesday is much larger than what is typically found in the state of Iowa.