SIOUX CITY, Iowa (AP) — The island nation of Micronesia is raising concerns about how some of its citizens working at an Iowa pork processing plant are being treated.

Micronesia recently sent a formal letter to the State Department asking U.S. officials to investigate possible misconduct at the Seaboard Triumph Foods plant, including verbal abuse, using false Social Security numbers and withholding workers’ passports.

The company denies any wrongdoing.

Micronesia said in its letter that dozens of its citizens have complained about the way they have been treated while working at the plant. Seaboard recruited workers from Micronesia.

The State Department didn’t immediately respond Tuesday to questions about its response to the complaint.