US amusement park SeaWorld has admitted some of its employees posed as animal activists to spy on its critics.
SeaWorld employee Paul McComb was briefly suspended in July after the People for the Ethical Treatment of Animals (PETA) accused him of trying to incite violence among peaceful protesters whilst posting as an activist.
SeaWorld chief executive Joel Manby said the company would no longer use such practices.
The company has faced intense criticism by animal rights activists who say it is enslaving marine animals at its 11 parks across the US.
"The board has directed that the company's management team end a practice in which certain employees posed as animal rights activists," Mr Manby announced on Thursday.
He said the decision to send people undercover was "to maintain the safety and security of company employees, customers, and animals in the face of credible threats that the company had received".
The company said Mr McComb had since returned to work in a different department.
PETA said the company's refusal to dismiss Mr McComb showed that it condoned corporate spying.
SeaWorld has been struggling with falling visitor numbers across its parks in the US since a critical documentary film, Blackfish, was released three years ago.
Public displays by killer whales, which have been the centrepiece at three parks operated in California, Florida and Texas, would be phased out under plans the company revealed in December.
Animal rights activists had argued keeping the mammals in captivity was cruel and unnecessary.