BUFFALO, N.Y.—A federal district court jury in Buffalo, N.Y., has awarded $25 million in damages to a black steel worker who claimed severe racial harassment over several years by co-workers, according to news reports.

Elijah Turley, who worked at a now-closed plant in Lackawanna, N.Y., operated by Luxembourg-based ArcelorMittal, testified during the three-week trial that “KKK” and “King Kong” graffiti were written on the walls of the plant and a stuffed monkey with a noose around its neck was found hanging from the driver's side mirror of his car, according to the reports. Mr. Turley said the harassment occurred between 2005 and 2008

ArcelorMittal said in a statement it has a “zero tolerance” policy for workplace discrimination and prior to the alleged incidents at the plant had developed a number of policies and training procedures to protect its employees and the company from such incidents.

It said the behavior experienced by Mr. Turley was unacceptable to company management, which upon learning of them “took prompt and documented remedial measures to investigate all internal complaints in an effort to stop and prevent recurrence.”

The company said it hired a third-party investigator, installed security cameras and shut down the operating line where the plaintiff worked to question employees and remind them of the company’s zero-tolerance policy.

“However, the company was unable to determine who was involved in the unacceptable behavior,” said the statement. “Management’s efforts were met with a ‘code of silence,’ meaning employees, including the plaintiff, did not provide information that would have allowed the company to pursue necessary action against those engaged in the inappropriate behavior.”

The statement said the compensatory and punitive damages awarded by the jury “far exceed what is normally allowed” under federal or state law, and that it is “pursuing all available post-trial options, including an appeal if necessary.”

Mr. Turley’s attorney could not be reached for comment.