Kilmarnock have contacted police after receiving a letter containing “racist abuse” directed at manager Alex Dyer.
The club say the letter was received on Monday morning.
“We are working with Police Scotland to identify any individuals involved in this disgusting act,” Kilmarnock said.
“And we will pursue the strongest possible action we can against them. Racism in any form is completely unacceptable and must be called out whenever and wherever it is found.”