After a six-month investigation prompted by the protests of student workers on an international exchange program, the Labor Department on Tuesday issued fines of $283,000 for health and safety violations against a company that operates a plant in Pennsylvania packing Hershey’s chocolates, saying it had covered up serious injuries to workers.

The 24-page citation by the Occupational Safety and Health Administration found that the company, Exel, intentionally failed to report 42 serious injuries over four years to workers at the plant in Palmyra, Pa., or 43 percent of all such injuries in that period at the plant. The injuries, which were discovered by safety inspectors during their investigation, required medical treatment, and many were related to lifting and moving big boxes of Hershey’s chocolates along a packing line.

The inquiry by the agency, known as OSHA, was spurred by protests last August by hundreds of foreign students working in the plant under an international cultural exchange program run by the State Department. The findings by OSHA against Exel are another black eye for the Hershey Company resulting from moves by its contractor and subcontractors to hire visiting foreign students as temporary laborers for strenuous work on fast-moving lines, packing Reese’s cups, Kit-Kat bars and Hershey’s Kisses.

The fines, which are high for workplace safety offenses, were levied because six of the nine violations were for willful failure by Exel to protect its workers. The agency did not say whether the injured workers included foreign students.