SHEFFIELD LAKE, Ohio — A black police officer in the US state of Ohio has filed a discrimination complaint after allegedly receiving a racist note from a superior officer, BBC reported.

Officer Keith Pool made the complaint after video footage emerged of then-Sheffield Lake Police Chief Anthony Campo placing a note on his desk reading "Ku Klux Klan" (KKK) last June.

It is also alleged Campo engaged in ongoing racist abuse against Pool.

Campo has since resigned and said his actions were "a joke".

Pool, who became Sheffield Lake's first black officer in 2020, told reporters during a press conference on Thursday that his initial reaction had been one of shock, simply asking the then police chief: "Are you serious?"

"What else can you say to the chief of police, who had done something so heinous and so awful to the first black officer ever? It's not understandable," he said.

Lawyers for Keith Pool, 57, allege that Mr Campo's actions formed part of a pattern of racist behavior.

They say this included wearing a pointy hat of the KKK - a white supremacist organisation — he made in front of colleagues, harassing Pool on an "ongoing basis" and creating racially offensive images mocking him and another officer, "the only Latino officer in the division".

Campo resigned from his position after being placed on leave by the town's mayor in July. At the time, he told local news outlet, Channel 5, that he had simply been joking during the incident.

"It was just a joke that got out of hand. I hired that officer on the force, he's excellent with children, and I helped to save his job after he was in danger of being let go by another department due to age restrictions," he said.

Pool has also alleged that superior officers were aware of the chief's behaviour, but made no attempt to stop the abuse.