The U.S. Equal Employment Opportunity Commission, a federal agency, said it was suing ExxonMobil after several nooses were discovered at the company's complex in Baton Rouge, La.

The EEOC said ExxonMobil failed to take action after a Black employee discovered a noose at his work station at the chemical plant in January 2020. At the time, it was the fourth noose uncovered at the Baton Rouge site — and a fifth was found at the end of that year.

ExxonMobil allegedly "investigated some, but not all, of the prior incidents and failed to take measures reasonably calculated to end the harassment" which resulted in "a racially hostile work environment," according to the EEOC's statement on Thursday. ExxonMobil's lack of action, the federal agency alleges, was a violation of Title VII of the Civil Rights Act of 1964.

"A noose is a longstanding symbol of violence associated with the lynching of African Americans," Elizabeth Owen, a senior trial attorney for the EEOC's New Orleans office, said in the statement. "Such symbols are inherently threatening and significantly alter the workplace environment for Black Americans."

"Even isolated displays of racially threatening symbols are unacceptable in American workplaces," Michael Kirkland, director of the EEOC's New Orleans field office, added.

ExxonMobil did not immediately respond to NPR's request for comment. On Friday, a company spokesperson told NBC News that it disagreed with the federal agency's findings.

"We encourage employees to report claims like this, and we thoroughly investigated," the spokesperson said. "The symbols of hate are unacceptable, offensive, and in violation of our corporate policies."

The EEOC filed the suit in the U.S. District Court for the Middle District of Louisiana, after it said it tried to reach a settlement.

The incident is one of several alarming discoveries of nooses on display in the past few years. In November, a noose was discovered at the Obama Presidential Center construction site in Chicago. In May 2022, a noose was found hanging from a tree at Stanford University. In May 2021, Amazon halted construction of a warehouse after several nooses were uncovered at a site in Connecticut. And in June 2020, nooses were found at a public park in Oakland, Calif.