Kilmarnock are investigating the alleged use of sectarian language by striker Kyle Lafferty.
A video circulating online shows the 35-year-old posing with a fan before allegedly making a sectarian comment.
Kilmarnock have now confirmed they are investigating the incident.
In a statement, the Rugby Park club said: “Kilmarnock Football Club are aware of a video circulating online which appears to show a member of our playing staff using language of a sectarian nature.
“The club finds all forms of discriminatory behaviour completely unacceptable. The matter will be investigated by the club.”
Lafferty is on international duty with Northern Ireland who face Kosovo on Saturday in the Nations League.