Linfield have issued a warning to fans following a number of "recent instances of unacceptable supporter behaviour" at games.
The club says it "totally condemns" the incidents which included the use of fireworks and sectarian and offensive chanting from a "small but vocal section of our supporters".
Linfield's Board of Directors met on Monday night to discuss recent issues before releasing a robust statement on Tuesday, just hours before the club's massive County Antrim Shield semi-final with Glentoran at Windsor Park.